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139 Cards in this Set
- Front
- Back
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What is a pituitary adenoma? |
It's a benign tumor of anterior pituitary cells that may be functional (hormone producing) or non-functional |
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How does nonfunctional tumors present? |
With mass effect: |
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How do functional tumors present? |
Features based on the type of hormone produced. |
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Most commonly produced pituitary tumor? |
Prolactinoma
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How does prolactinoma present?
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Causes GnRH inhibition --> less LH and FSH release |
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Treatment for prolactinoma
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+ dopamine agonists: bromocriptine or cabergoline to suppress prolactin production --> shrinks tumor
+ surgery for larger lesions |
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How does growth hormone adenoma present?
a/w? |
+ gigantism in children - increased linear bone growth (epiphyses not fused)
+ acromegaly in adults - enlarged bones of hands feet and jaw, visceral organ growth --> dysfunction (e.g. cardiac failure), enlarged tongue + Secondary diabetes due to peripheral tissue not picking up glucose in response to GH (GH induces liver gluconeogenesis) |
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Diagnosis of GH?
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+ increased GH and IGF
+ lack of GH suppression of glucose test |
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Treatment of growth hormone adenoma?
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+ octreotide (somatostatin analogue that inhibits anterior pituitary secretion of hormones)
+ GH receptor antagonists + surgery |
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What is hypopituitarism?
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+ insufficient production of hormones by the anterior pituitary gland.
+ symptoms arise when +75% parenchyma is lost |
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What are the causes of hypopituitarism?
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+ Pituitary adenomas (adult) or craniopharyngoma (children)
+ Sheehan syndrome + Empty sella syndrome |
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Why does a pituitary adenoma or craniopharyngioma cause hypopituitarism?
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+ mass effect or pituitary apoplexy (bleeding into an adenoma) --> loss of or compression of pituitary tissue
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What is Sheehan syndrome and how does it cause hypopituitarism?
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+ pregnancy related pituitary infarction resulting from lack of blood supply increase in relation to gland hypertrophy
+ presents with lack of milk letdown and loss of pubic hair |
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What is empty sella syndrome and how does it cause hypopituitarism?
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+ it is a congenital defect of the sella
+ herniation of the arachnoid and CSF into the sella compresses and destroys the pituitary gland + pituitary gland is absent on imaging |
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What hormones are released from the posterior pituitary and what are their roles?
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+ ADH : acts on distal tubules and collecting ducts of the kidney to promote free water retention
+ Oxytocin: uterine contraction during labor and milk let down in lactating mothers |
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Where are ADH and oxytocin made?
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hypothalamus and transported via axons to be released in the posterior pituitary
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What is central diabetes insipidus and what are its causes?
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+ ADH deficiency
Causes: + hypothalamic or posterior pituitary pathology (tumor, trauma, infection or inflammation) |
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What are the clinical features of central diabetes insipidus?
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(based on loss of free water)
+ polyuria and polydipsia with risk of life-threatening dehydration + hypernatremia and high serum osmolality + low urine osmolality and specific gravity |
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How do you diagnose central diabetes insipidus?
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water deprivation test fails to increase urine osmolality
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What is the treatment for central diabetes insipidus?
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desmopressin (ADH analog)
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What is nephrogenic diabetes insipidus and what are its causes?
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+ impaired renal response to ADH
causes: inherited mutations or drugs (lithium and demeclocycline) |
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How do you differentiate central from nephrogenic diabetes insipidus?
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only central diabetes insipidus responds to desmopressin
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What is Syndrome of Inappropriate ADH Secretion and what are its causes?
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+ excess ADH secreted inappropriately.
+ cause is often ectopic production: small cell carcinoma, but can also be due to CNS trauma, pulmonary infection and drugs (cyclophosphamide) |
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What are SIADH symptoms?
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(retention of free water)
+ Hyponatremia and low serum osmolality. + Mental status changes and seizures -- hyponatremia leads to neuronal swelling and cerebral edema |
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How is the treatment for SIADH?
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water restriction or demeclocycline(off-label use)
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What is a thyroglossal duct cyst and how does it present?
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Cystic dilation of thyroglossal duct remnant and presents as a anterior neck mass
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Describe the development of the thyroid
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+ it develops at the base of the tongue and travels along the thyroglossal duct to the anterior neck.
+ the thyroglossal duct normally involutes, but if it persists it may undergo cystic dilation |
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What is a lingual thyroid and how does it present?
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It is the persistence of thyroid tissue at the base of the tongue and presents as a base of tongue mass
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What is hyperthyroidism
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+ Increased BMR by increasing synthesis of Na+/K+ ATPase
+ Increases sympathetic nervous system activity via increased expression of beta-1 adrenergic receptors |
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Symptoms of hyperthyroidism
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Weight loss (despite increased appetite) |
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What is graves disease?
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+ AutoAb (IgG) that stimulates TSH (type II hypersensitivity --> increased synthesis and release of TH
+ most common cause of hyperthyroidism |
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Grave's Disease demographic
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Women of childbearing age(20-40 years)
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grave's disease symptoms
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+ hyperthyroidism
+ Diffuse goiter + Exophthalmos and pretibial myxedema |
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Why does Graves cause goiters?
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constant TSH stimulation leads to thyroid hyperplasia and hypertrophy
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Why does Graves cause exophthalamos and pretibial myxedema?
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Fibroblasts behind eye and shin have TSH receptors. When antibodies bind to these receptors, they are induced to secrete more glycosaminoglycans (chondroitin sulfate and hyaluronic acid) which cause the symptoms
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Graves disease lab findings
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+ histo: irregular follicles with scalloped colloid and chronic inflammation
+ increased total and free T4 + decreased TSH + hypocholestolemia + increased serum glucose |
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Why is there decreased TSH in Graves disease?
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free T4 downregulates TRH receptors in anterior pituitary to decrease TSH release
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What is the treatment for grave's?
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+ beta blockers
+ Thioamide (blocks thyroid peroxidase) + radioiodine ablation |
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What is thyroid storm?
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+ potentially fatal complication that is due to elevated catecholamines and massive hormone excess in response to stress (surgery or childbirth)
+ presents as arrhthmia, hyperthermia and comiting with hypovolemic shock |
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Treatment for thyroid storm
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+ PTU=propylthiouracil - inhibits peroxidase- mediated oxidation, organification and couple steps of TH synthesis (and peripheral conversion of T4 to T3)
+ beta blockers + steroids |
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What is a multinodular goiter?
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+ enlarged thyroid gland with mutiple nodules that is usually nontoxic
+ rarely becomes TSH independent leading to T4 release and hyperthyroidism |
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What causes multinodular goiter?
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relative iodine deficiency
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What is cretinism and what are its clinical features?
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+ hypothyroidism in neonates and infants
+ mental retardation, short stature with skeletal abnormalities, coarse facial features, enlarged tongue and umbilical hernia + TH is needed for normal brain and skeletal development |
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What are the causes of cretinism?
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+ maternal hypothyroidism during early pregnancy
+ thyroid agenesis + dyshormonogenetic goiter (due to congenital defect in TH production and involves thyroid peroxidase) + iodine deficiency |
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What is myxedema and its causes?
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+ hypothyroidism in older children or adults, accumulation of glycosaminoglycans in skin and soft tissues
+ causes: iodine deficiency, Hashimoto thyroiditis, drugs (lithium), surgical removal or radioablation of the thyroid |
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What are clinical features of myxedema?
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+ decrease BMR and SNS
+ deepening of voice and large tongue + weight gain + slowing of mental activity + muscle weakness + cold intolerance with decreased sweating + bradycardia with decreased CO --> SoB and fatigue + oligomenorrhea + Hypercholesterolemia + Constipation |
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What is Hashimoto's thyroiditis?
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AI destruction of thyroid gland associated with HLA-DR5, occurring in regions where I2 levels are adequate
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What are the clinical features of Hashimoto Thyroiditis?
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+ initially hyperthyroidism (due to follicle damage)
+ progresses to hypothyroidism (dec. T4 and inc. TSH) + antithyroglobulin and antimicrosomal antibodies are often present (thyroid damage sign) + increased risk of B cell (marginal zone) lymphoma (enlarging thyroid gland) |
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What does histology of hashimoto's thyroiditis show?
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+ chronic inflammation with germinal centers and Hurthle cells (eosinophillic metaplasia of cells that line follicles)
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What is subacute granulomatous (de quervain) thyroiditis?
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+ Granulomatous thyroiditis that follows viral infection
+ tender thyroid with transient hyperthyroidism + self-limited, does not progress to hypothyroidism |
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What is reidel fibrosing thyroiditis?
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+ chronic inflammation with extensive fibrosis of thyroid gland
+ hypothyroidism ("hard as wood" nontender thyroid gland) + fibrosis involving local structures --> clinically mimics anaplastic carcinoma but absent malignant cells and younger (40s) patients |
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How does thyroid neoplasia usually present?
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+ distinct, solitary nodules
+ benign > malignant |
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How are 131 I radioactive uptake studies used to further characterize nodules?
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increased uptake ("hot" nodule) - Grave's disease or nodular goiter
Decreased uptake ("cold" nodule) - adenoma and carcinoma, warranting biopsy by fine needle aspiration |
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What is follicular adenoma
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+ benign proliferation of follicles surrounded by a fibrous capsule
+ usually nonfunctional, but may secrete TH |
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What is papillary carcinoma?
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+ most common type of thyroid carcinoma
+ ionizing radiation in childhood is a major risk factor + papillae lined by cells with clear "Orphan Annie eye" nuclei and nuclear grooves + papillae associated with psammoma bodies + spreads to cervical lymph nodes + excellent prognosis |
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What is follicular carcinoma?
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+ malignant proliferation of follicles surrounded by a fibrous capsule with invasion through capsule to distinguishing follicular carcinoma from follicular adenoma (cannot be done with FNA)
+ hematogenous metastasis |
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What is medullary carcinoma?
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malignant proliferation of parafollicular C cells (5% thyroid carcinomas) --> hypocalcemia or amyloid deposits in tumor
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What are C cells?
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+ neuroendocrine cells that secrete calcitonin (lowers serum calcium by increasing renal calcium excretion, but inactive at normal physiological levels)
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What does a biopsy of medullary carcinoma show?
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malignant cells in an amyloid stroma
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What genes are associated with familial causes of medullary carcinoma?
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MEN (multiple endocrine neoplasia) 2A and 2B, associated with mutations in the RET oncogene
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What is MEN 2 associated with?
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medullary carcinoma, pheochromocytoma and parathyroid adenoma (2A) or ganglioneuromas of the oral mucosa (2B)
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What should you do if you detect a RET mutation?
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prophylactic thyroidectomy
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What is anaplastic carcinoma?
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+ undifferentiated maligant tumor of the thyroid (elderly unlike reidels)
+ invades local structures --> dysphagia or respiratory compromise + poor prognosis |
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What are chief cells?
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they are cells of the parathyroid gland that regulate serum free calcium via PTH secretion
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What does PTH secretion do?
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+ increases bone osteoclast activity, releasing Ca and PO4
+ increasing small bowel absorption of Ca and PO4 (indirectly via Vit D) + increasing renal Ca++ reabsorption (distal tubule) and decreases phosphate reabsorption (proximal tubule) |
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Describe the control of PTH secretion
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increased serum ionized Ca++ provides negative feedback to decrease PTH
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What is primary hyperparathyroidism and what are its causes?
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+ excess PTH due to a disorder of the parathyroid gland |
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what are some of the features of a parathyroid adenoma?
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+ benign neoplasm, involving one gland
+ usually asymptomatic hypercalcemia + may present with consequence of increased PTH and hypercalcemia: nephrolithiasis, nephrocalcinosis, CNS disturbances, constipation, peptic ulcer disease, acute pancreatitis, osteitis fibrosa cystica (resorption of bone leading to fibrosis and cystic spaces) |
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What are lab findings in primary hyperparathyroidism?
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increased serum PTH
increased serum Ca++ decreased serum PO4 increased urinary cAMP increased serum alkaline phosphatase |
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What is the treatment of primary hyperparathyroidism?
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surgical removal of affected gland
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what is secondary hyperparathyroidism?
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Excess production of PTH due to a disease process extrinsic to the parathyroid gland
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what are causes of secondary hyperparathyroidism?
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chronic renal failure --> decreased phosphate excretion --> increased serum phosphate --> binds free calcium --> dec. free calcium --> stimulates all four parathyroid glands --> bone resorption
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what are lab findings in secondary hyperparathyroidism?
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increased serum PTH
decreased serum Ca++ increased serum PO4 increased serum alkaline phosphatase |
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what is hypoparathyroidism and what are the causes?
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+ low PTH
+ causes: AI damage to parathyroids, surgical excision and DiGeorge syndrome |
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How does hypoparathyroid present?
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low serum calcium
numbness and tingling (particularly circumoral) muscle spasms (tetany) - facial nerve tapping (Chvostek sign) |
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What are lab findings in hypoparathyroidism?
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decreased PTH
decreased serum calcium |
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What is the cause of pseudohypoparathyroidism?
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end-organ resistance to PTH
AD form associated with short stature and short 4th and 5th digits |
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What do labs reveal in cases of pseudohypoparathyroidism?
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hypocalcemia with increased PTH
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What major hormones are produced by the endocrine pancreas and what part of the islet of langerhans do they come from?
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+ insulin - beta cells - center of islets
+ glucagon - alpha cells |
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What are the effects of insulin?
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l. upregulates insulin-dependent glucose transporter protein (GLUT4) on skeletal muscle and adipose tissue (glucose uptake by GLUT4 decreases serum glucose)
2. Increased glucose uptake by tissues leads to increased glycogen synthesis, protein synthesis, and lipogenesis. |
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What are the effects of glucagon?
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it opposes insulin in order to increase blood
glucose levels (e.g., in states of fasting) via glycogenolysis and lipolysis. |
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What is type I diabetes mellitus?
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Insulin deficiency leading to a metabolic disorder characterized by hyperglycemia
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What is the cause of type I DM?
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Due to autoimmune destruction of beta cells by T lymphocytes
l. Characterized by inflammation of islets 2. Associated with HLA-DR3 and HLA-DR4 3. AutoAbs against insulin are often present (sign of damage) and may be seen years before clinical disease develops. |
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What are the clinical manifestations of insulin deficiency?
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l. High serum glucose |
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How does insulin deficiency lead to weight loss, low muscle mass and polyphagia?
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Unopposed glucagon leads to gluconeogenesis, glycogenolysis and lipolysis, which further exacerbates hyperglycemia.
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How does insulin deficiency lead to polyuria, polydipsia, and glycosuria?
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Hyperglycemia exceeds renal ability to resorb glucose; excess filtered glucose leads to osmotic diuresis.
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What is the treatment of diabetes mellitus type I?
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lifelong insulin
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What is diabetic ketoacidosis and its causes?
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it is a complication of diabetes that is characterized by excessive serum ketones
arises with stress (e.g., infection); epinephrine stimulates glucagon secretion increasing lipolysis (along with gluconeogenesis and glycogenolysis). i. Increased lipolysis --> increased FFAs ii. Liver converts FFAs to ketone bodies |
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What are symptoms of diabetic ketoacidosis?
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+ hyperglycemia(> 300 mg/dL), anion gap metabolic acidosis, and hyperkalemia
+ presents with Kussmaul respirations, dehydration, nausea, vomiting, mental status changes, and fruity smelling breath (due to acetone) |
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What is the treatment for diabetic ketoacidosis?
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fluids (corrects dehydration from polyuria), insulin, and replacement of electrolytes (e.g., potassium)
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What is type II diabetes mellitus and who is at the greatest risk?
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End-organ insulin resistance leading to a metabolic disorder characterized by hyperglycemia
middle-aged, obese adults, especially those that have a genetic predisposition |
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How are insulin levels affected by type II diabetes mellitus?
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Insulin levels are increased early in disease, but later, insulin deficiency develops due to beta cell exhaustion
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What does histology reveal in type II diabetes mellitus?
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amyloid deposition in the islets
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What are clinical features of type II diabetes mellitus?
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polyuria, polydipsia, and hyperglycemia, but disease is
often clinically silent. |
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How do you diagnose type II diabetes mellitus?
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measuring glucose levels (normal is 70-120 mg/dL).
1. Random glucose > 200 mg/dL 2. Fasting glucose > 126 mg/dL 3. Glucose tolerance test with a serum glucose level > 200 mg/dL two hours after glucose loading |
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What is the treatment of type II diabetes mellitus?
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weight loss (diet and exercise) initially; may require drug therapy
to counter insulin resistance (e.g., sulfonylureas or metformin) or exogenous insulin after exhaustion of beta cells |
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What is hyperosmolar-non-ketotic coma?
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a risk complication of type II diabetes in which high glucose(> 500 mg/dL) leads to life-threatening diuresis with hypotension and coma.
Ketones are absent due to small amounts of circulating insulin |
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What are some long term consequences of diabetes?
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+ nonenzymatic glycosylation of vascular basement membrane
+ osmotic damage |
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What does NEG of large and medium sized vessels lead to?
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atherosclerosis and its resultant complications; cardiovascular disease, peripheral vascular disease (nontraumatic amputations)
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What does NEG of small sized vessels lead to?
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hyaline arteriolosclerosis |
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What does NEG of hemoglobin lead to?
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glycated hemoglobin (HbA1c), which serves as a marker of glycemic control
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How does diabetes lead to osmotic damage and what are the resulting clinical manifestations?
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1. Glucose freely enters into Schwann cells (which myelinate peripheral nerves), pericytes of retinal blood vessels, and the lens.
2. Aldose reductase converts glucose to sorbitol, resulting in osmotic damage. 3. Leads to peripheral neuropathy, impotence, blindness, and cataracts |
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What diseases is MEN1 associated with?
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pancreatic endocrine neoplasms
parathyroid hyperplasia pituitary adenomas |
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How do insulinomas present?
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episodic hypoglycemia with mental status changes that are relieved by administration of glucose.
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How are insulinomas diagnosed?
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decreased serum glucose (<50 mg/dL), increased insulin and increased C-peptide
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How do gastrinomas present?
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treatment-resistant peptic ulcers (Zollinger-Ellison
syndrome); ulcers may be multiple and can extend into the jejunum |
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How do somatostatinomas present?
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achlorhydria (due to inhibition of gastrin) and
cholelithiasis with steatorrhea (due to inhibition of cholecystokinin). |
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How do VIPomas present?
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secrete excessive vasoactive intestinal peptide leading to watery diarrhea, hypokalemia, and achlorhydria
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What are the layers of the adrenal cortex and what hormones associated with each layer?
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1. Glomerulosa produces mineralocorticoids (e.g., aldosterone).
2. Fasciculata produces glucocorticoids (e.g. cortisol). 3. Reticularis produces sex steroids (e.g. testosterone). |
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What is cushing syndrome and what are the clinical features?
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A. Hypercortisolism
B. Clinical features: 1. Muscle weakness with thin extremities 2. Moon facies, buffalo hump, and truncal obesity 3. Abdominal striae 4. Hypertension 5. Osteoporosis 6. Immune suppression |
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How does Cushing syndrome lead to muscle weakness?
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Cortisol breaks down muscle for gluconeogenesis.
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How does Cushing syndrome lead to truncal obesity?
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High insulin (due to high glucose) increases storage of fat.
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How does Cushing syndrome lead to abdominal striae?
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Due to impaired synthesis of collagen with thinning of skin
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How do you diagnose Cushing's syndrome?
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increased 24-hour urine cortisol levels
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What are the causes of Cushing's syndrome?
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l. Exogenous corticosteroids
2. Primary adrenal adenoma, hyperplasia, or carcinoma 3. ACTH-secreting pituitary adenoma 4. Para neoplastic ACTH secretion (e.g., small cell carcinoma of the lung) |
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What are the consequences of exogenous corticosteroids?
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Bilateral adrenal atrophy; steroids suppress
ACTH secretion (negative feedback). |
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What are the consequences of primary adrenal adenoma, hyperplasia, or carcinoma
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leads to atrophy of the uninvolved adrenal gland
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What are the consequences of ACTH-secreting pituitary adenoma?
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leads to bilateral adrenal hyperplasia
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What are the consequences of para neoplastic ACTH secretion
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leads to bilateral adrenal hyperplasia
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How does dexamethasone work?
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High-dose dexamethasone (cortisol analog) suppresses ACTH production by a pituitary adenoma (cortisol levels decrease), but fails to suppress ectopic ACTH production by a small cell lung carcinoma (cortisol levels remain high).
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What is Conn's syndrome and how does it present?
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A. Excess aldosterone
B. Presents as hypertension with hypernatremia, hypokalemia, and metabolic alkalosis |
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How does aldosterone lead to hypertension?
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l. Aldosterone increases sodium absorption and secretion of potassium and hydrogen ions (distal tubules and collecting duct).
2. Increased absorption of sodium expands plasma volume leading to hypertension. |
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What is the cause of primary hyperaldosteronism?
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adrenal adenoma;
sporadic adrenal hyperplasia and adrenal carcinoma are less common causes. |
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How do primary and secondary hyperaldosteronism compare in levels of aldosterone and renin?
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primary: high aldosterone and low renin (high blood pressure downregulates renin via negative feedback)
secondary: high aldosterone and high renin |
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What is the cause of secondary hyperaldosteronism?
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activation of the renin-angiotensin system (e.g., renovascular hypertension or CHF)
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What is congenital adrenal hyperplasia and what are its causes?
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Excess sex steroids with hyperplasia of both adrenal glands
Causes: Inherited 21-hydroxylase deficiency |
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How does 21-hydroxylase deficiency leading to congenital adrenal hyperplasia?
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1. 21-hydroxylase is required for the production of aldosterone and corticosteroids.
2. In enzyme deficiency, steroidogenesis is predominantly shunted toward sex steroid production (which does not require 21-hydroxylase). 3. Deficiency of cortisol leads to increased ACTH secretion (lack of negative feedback), which results in bilateral adrenal hyperplasia. |
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What are clinical features of congenital adrenal hyperplasia?
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Salt wasting with hyponatremia, hyperkalemia, and hypovolemia due to lack of aldosterone.
2. Life-threatening hypotension due to lack of cortisol. 3. Clitoral enlargement (females) or precocious puberty (males) due to excess androgens |
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What is adrenal insufficiency and what are its causes?
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A. Lack of adrenal hormones
B. Acute insufficiency may arise with Waterhouse-Friderichsen syndrome. C. Chronic insufficiency (Addison disease) is due to progressive destruction of the adrenal glands. |
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What are the clinical manifestations of Waterhouse-Friderichsen syndrome?
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l. Characterized by hemorrhagic necrosis of the adrenal glands classically due to DIC in young children with N meningitidis infection
2. Lack of cortisol exacerbates hypotension, often leading to death |
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What are the causes of progressive destruction of adrenal glands?
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autoimmune destruction (most common cause in |
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What are clinical features of Addison's disease?
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hypotension, hyponatremia, hypovolemia,
hyperkalemia, weakness, hyperpigmentation (increased ACTH by-products stimulate melanocytic production of pigment), vomiting, and diarrhea. |
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What cells make of the adrenal medulla and what hormones are produced?
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A. Composed of neural crest-derived chromaffin cells
B. Main physiologic source of catecholamines (epinephrine and norepinephrine) |
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What is pheochromocytoma?
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Tumor of chromaffin cells
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What are the clinical features of pheochromocytoma?
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clinical features are due to increased serum catecholamines.
l. Episodic hypertension, headache, palpitations, tachycardia, and sweating |
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How do you diagnose pheochromocytoma?
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Increased serum metanephrines and increased 24-hour urine metanephrines and vanillylmandelic acid
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How do you treat pheochromocytoma?
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Surgical excision
l. Catecholamines may leak into the bloodstream upon manipulation of the tumor. 2. Phenoxybenzamine (irreversible a-blocker) is administered perioperatively to prevent a hypertensive crisis. |
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What is the rule of 10s in the presentation of pheochromocytoma?
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10% bilateral, 10% familial, 10% malignant, and 10% located outside of the adrenal medulla (e.g., bladder wall or organ of Zuckerkandl at the inferior mesenteric artery root)
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What is pheochromocytoma associated with?
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MEN 2A and 2B, von Hippel-Lindau disease, and neurofibromatosis type 1
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