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63 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:
+ Bitemporal hemianopsia which occurs due to compression of the optic chiasm + Hypopituitarism due to compression of normal pituitary tissue + Headache |
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How do functional tumors present?
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Features based on the type of hormone produced.
In the pituitary, these can be prolactinomas, growth hormone cell adenomas, ACTH cell adenomas. Rare: TSH cell ademonas, LH-producing adenomas, FSH-producing adenomas |
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Most commonly produced pituitary tumor?
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Prolactinoma
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How does prolactinoma present?
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Causes GnRH inhibition --> less LH and FSH release
Galactorrhea and amenorrhea(females) Decreased libido and headache (males) |
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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)
Heat intolerance + sweating Tachycardia with increased CO Arrhythmia Tremor, anxiety, insomnia, heightened emotions Staring gaze with lid lag Diarrhea with malabsorption Oligomenorrhea Bone resorption with hypercalcemia Decreased muscle mass with weakness HYPOcholesterolemia HYPERglycemia (increased gluconeogenesis and glycogenolysis) |
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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) |
