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92 Cards in this Set

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