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92 Cards in this Set
- Front
- Back
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hypocalcemia, elevated phosphorus and normal serum albumin
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hypoparathyroidism
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signs of hypocalcemia
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seizures, muscular pain and cramps, positive Cvostek or Trousseau, laryngospasm
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what is a Chvostek sign?
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tapping on the facial nerve results in contraction of the mouth and orbicularis oris
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Trousseau sign
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production of a carpopedal spasm of the hand by a partially inflated tourniquet on the arm (>2 min)
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What is autosomal recessive polyglandular autoimmune syndrome type 1?
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autoimmune polyendocrinopathy, candidiasis and ectodermal dysplasia
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what would be serum phosphorus level in vitamin D deficiency?
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decreased
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What causes PTH secretion?
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Low levels of serum calcium
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What is the name of the enzyme that hydroxylates vit D2 and D3 at the 25 position?
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a cytochrome P-450-vitamin D-25-hydroxylase enzyme
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How does liver disease result in calcium problems?
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Interferes with 25-hydroxylation of vit D2 and D3
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What does cytochrome P-450-monooxygenase 25-hydroxy1-alpha-hydroxylase do?
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converts 25-hydroxyvitamin D to 1-alpha,25-dihydroxyvitamin
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What causes resistance to 1-alpha,25-dihydroxyvitamin D?
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mutations in vitamin D receptor gene
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How does malignancy result in hypercalcemia and hypophosphatemia?
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Islet cell tumors and pheochromocytomas produce Parathyroid Hormone-Related Protein which acts like PTH.
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Where does calcitonin come from?
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Secreted by the C cells of the thyroid gland
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What causes calcitonin to be secreted?
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An acute increase in serum calcium levels
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What are the actions of calcitonin?
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Inhibits osteoclastic resorption, producing hypocalcemia and hypophosphatemia.
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How does hypoparathyroidism present?
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Seizure, numbness and tingling sensations in the extremities, Chvostek sign, Trousseau sign, laryngospasm, bronchospasm, and prolonged QT
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What are the lab values for calcium and phosphate in hypoparathyroidism?
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Hypocalcemia and hyperphosphatemia
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What is APECED?
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Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome
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How does APECED present?
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Mucocutaneous candidiasis may precede development of hypoparathyroidism; other endocrinopathies include hypoadrenalism, hypogonadism, hypothyroidism, and diabetes mellitus
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What causes early neonatal hypocalcemia (first 3 days of life)?
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Agenesis or hypoplasia of parathyroid gland; preterm delivery with low birth weight, birth asphyxia, and presence of diabetes in the mother.
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What is DiGeorge Syndrome?
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Congenital absence of thymus and parathyroid glands and deficient cell-mediated immunity; cardiovascular malformations involving the aortic arch e.g. truncus arteriosis or aortic arch syndrome, dysmorphic features.
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What are the dysmorphic features associated with Digeorge syndrome?
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low-set ears, short philtrum, micrognathia, and a small “fish-like” mouth.
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What is velocardiofacial syndrome?
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facial dysmorphisms, palatal abnormalities, congenital heart disease, and other clinical findings c/w DiGeorge syndrome.
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What causes late hypocalcemia (after 5th day of life)?
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Secondary to hypoparathyroidism of any cause, maternal hyperparathyroidism, increased phosphorus intake
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Which acute illnesses cause hypoparathyroidism?
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Acute illnesses, including gram-negative sepsis, toxic shock syndrome, AIDS, and SARS often are associated with hypocalcemia secondary to hypoparathyroidism.
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What is AD Hypoparathyroidism?
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a rare form of hypocalcemia caused by a gain of function mutation in the calcium-sensing receptor.
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How does magnesium deficiency affect calcium levels?
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Chronic magnesium deficiency results in diminished production and effectiveness of PTH. Acute onset hypomagnesemia increases production of PTH.
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Why are total serum calcium levels not as reliable as levels of ionized calcium?
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Total serum calcium measurement affected by hypoalbuminemia, fluctuations in the pH, and the presence of radiographic contrast media
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What other metabolic abnormalities are found in people with hypomagnesemia?
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Hypokalemia
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What is pseudohypoparathyroidism?
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end-organ resistance to PTH action
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What lab abnormalities are found in pseudohypoparathyroidism?
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Hypocalcemia, hyperphosphatemia, elevated PTH
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How do you treat hypocalcemia?
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Initially, 10% calcium gluconate IV
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How do you infuse calcium gluconate?
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slowly with an EKG monitor -- watch for bradycardia and extravasation
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How does hyperparathyroidism initially present?
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Neuromuscular: Muscle weakness, paralysis, or hyporeflexia; Gastrointestinal: constipation, anorexia, and nausea; Renal: adverse affect on ADH action resulting in development of polyuria and polydipsia; CV: bradycardia and a reduced QT interval
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Long term consequence of hyperparathyroidism?
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Nephrocalcinosis
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What effect does a parathyroid adenoma have?
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Hypercalcemia secondary to hyperparathyroidism
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Causes of hyperparathyroidism
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parathyroid adenoma, parathyroid gland chief cell hyperplasia, chronic renal disease, sex-linked hypophosphatemic rickets
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Multiple endocrine neoplasia (MEN) 1
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neoplasia of pancreas, anterior pituitary glanda and parathyroid gland
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What is inheritance pattern of MEN 1
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AD with high penetrance and variable expression
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Multiple endocrine neoplasia (MEN) 2
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medullary carcinoma of the thyroid gland, pheochromocytoma and hyperparathyroidism
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Familial hypocalciuric hypercalcemia
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autosomal dominant, asymptomatic; no treatment required
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Williams syndrome
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SGA, facial abnormalities, hypotonia, developmental and motor retardation, supravalvular aortic stenosis, and a gregarious and friendly character (“cocktail party” personality); hypercalcemia that resolves by the end of the first year of life.
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Idiopathic Infantile Hypercalcemia
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possibly due to excessive maternal supplementation of vitamin D during pregnancy; birth defects similar to those seen in Williams syndrome.
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Immobilization Hypercalcemia
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infrequent; may produce hypercalcemia and hypercalciuria; treatment is ambulation
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Severe infantile hypophosphatasia
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AR, mutations in the alkaline phosphatase gene result in deficient mineralization and rickets. Hypercalcemia,
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How do Granulomatous Disorders result in hypercalcemia?
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The macrophages involved in the granuloma produce increased amounts of 1-alpha,25-dihydroxyvitamin D.
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Treatment of hypercalcemia
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hydration, furosemide, glucocorticoids (decrease intestinal absorption of calcium)
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Symptoms of hypercalcemia
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polyuria and thirst, headache, nausea and mental status changes, proximal muscle weakness, hallucinations, paralytic ileus, renal stones, nephrogenic DI, bone pain, pruritis,
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How does Prolonged immobilization lead to hypercalcemia?
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The mechanism, which is not understood entirely, relates to increased release of bone calcium in individuals who have high bone turnover.
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How does Hypercalcemia result in polyuria?
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Hypercalcemia causes a urinary concentrating defect by inhibiting vasopressin action.
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How is hypercalcemia treated?
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Saline duresis and loop diuretic
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What is pamidronate?
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IV or oral bisphosphonate
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What is alendronate?
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Oral bisphosphonate
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What do bisphosphonates do?
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adsorbed onto hydroxyapatite crystals in bone mineral, decrease bone resorption by inhibiting both osteoclast recruitment and activity, and by shortening of the life span of osteoclasts
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What are the three targets for regulation of calcium?
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the bones, renal filtration and reabsorption, and intestinal absorption
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Which regulators increase serum calcium?
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parathyroid hormone (PTH) and vitamin D
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What does calcitonin do to serum calcium?
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decreases
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Which organ regulates calcium changes rapidly?
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Kidney
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Which organ regulates calcium homeostasis long-term?
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Intestine
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What happens to PTH if serum calcium increases?
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Secretion of PTH is suppressed
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What are the actions of PTH (4):
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increases osteolytic release of calcium from bone directly, up regulates osteoclasts, increases calium reabsorption in loop of Henle and distal tubule, stimulates conversion of 25-hydroxyvitamin D to the active metabolite 1,25-dihydroxyvitamin D
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What is vitamin D-3?
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Cholecalciferol
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Where is cholecalciferol produced?
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In the skin
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From what is cholecalciferol produced?
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Action of UV light on 7-dehydrocholesterol
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What does the liver do to previtamin D?
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It 25-hydroxylates it.
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What is 25-hydroxyvitamin D?
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calcidiol
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What does the kidney do to calcidiol?
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It 1-hydroxylates it
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What is 1,25-dihydroxyvitamin D?
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calcitriol
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What does calcitriol do?
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Promotes intestinal absorption of calcium and phosphate, increases bone mineralization, increases calcium reabsorption in kidney
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What is the primary function of PTH?
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To increase serum calcium
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What does PTH do to phosphate?
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Inhibits reabsorption in kidney, lowers serum phosphate
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What change in phosphate level stimulates PTH?
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increase
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What change in calcium level stimulates PTH?
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decrease
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What inhibits Vitamin D3?
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phosphate and corticosteroids
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How does calcitonin decrease serum calcium?
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Impairs osteoclasts and prevents their formation, increases urinary calcium excretion
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How does metabolic alkalosis affect serum calcium?
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Increases tubular calcium reabsorption
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How do cytokines affect serum calcium?
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Stimulates osteoclasts
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How do prostaglandins affect serum calcium?
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Stimulates osteoclasts
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How does estrogen affect serum calcium?
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Inhibits bone resorption
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Causes of hypercalcemia in neonates
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Neonatal Primary hyperparathyroidism, Familial hypocalciuric hypercalcemia (FHH), excessive supplementation, Williams syndrome, blue diaper syndrome, secondary hyperparathyroidism
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What causes neonatal primary hyperparathyroidism?
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mutation in calcium-sensing receptor
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What is FHH?
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AD mutation of calcium receptor gene; often asymptomatic
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What is Williams syndrome?
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Deletion in elastin gene on chromosome 7, associated with elfin facies, mental retardation and supravalvular aortic stenosis
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Hypercalcemia results in hypo- or hyper-reflexia?
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Hyporeflexia
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When does the hypercalcemia associated with Williams syndrome resolve?
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by 9-18 months
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How is hypercalcemia associated with Williams syndrome treated?
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Dietary restriction
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What is blue diaper syndrome?
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A selective defect in the intestinal transport of tryptophan, results in hypercalcemia
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What is secondary hyperparathyroidism?
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Neonatal response to maternal hypocalcemia—child progresses from hypocalcemia to normocalcemia to hypercalcemia quickly after birth
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Etiology of hypercalcemia in infants
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subcutaneous fat necrosis
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Etiology of hypercalcemia in school age children
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hyperparathyroidism; MEN, type 1
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Which diuretics can cause hypercalcemia?
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thiazides
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How does acidosis affect serum calcium measurement?
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Increases level of ionized calcium, does not increase total calcium
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