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IM - CALCIUM IMBALANCE

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tonystep1's version from 2017-08-01 05:24

DIFFERENTIAL FOR HYPO/HYPERCALCEMIA

Question Answer
Hypocalcemia. Hypoparathyroidism (most common cause)-usually due to surgery on the thyroid gland (with damage to nearby parathyroids) 2. Acute pancreatitis-Deposition of calcium deposits lowers serum Ca2+ levels.3. Renal insufficiency-mainly due to decreased production of 1 ,25-dihydroxy vitamin D 4. Hyperphosphatemia-P043- precipitates with Ca2+ , resulting in calcium phosphate deposition. 5 Vitamin D Deficiency
Hypercalcemia EndocrinopathiesHyperparathyroidism-increased CaH , low P043- b. Renal failure-usually results in hypocalcemia, but sometimes secondary hyperparathyroidism elevates PTH levels high enough to cause hypercalcemia c. Paget's disease of the bone-due to osteoclastic bone resorption d. Hyperparathyroidism, acromegaly, Addison's disease
Hypercalcemia MalignanciesMetastatic cancer-Bony metastases result in bone destruction due to osteoclastic activity. Most tumors that metastasize to bone cause both osteolytic and osteoblastic activity (prostate cancer, mainly osteoblastic; kidney carcinoma, usually osteolytic) . b. Multiple myeloma-secondary to two causes • Lysis of bone by tumor cells • Release of osteoclast-activating factor by myeloma cells c. Tumors that release PTH-like hormone (e.g., lung cancer)
Hypercalcemia Pharmacologica. Vitamin D intoxication-increased GI absorption of calcium b. Milk-alkali syndrome-hypercalcemia, alkalosis, and renal impairment due to excessive intake of calcium and certain absorbable antacids (calcium carbonate, milk) c. Drugs-thiazide diuretics (inhibit renal excretion) , lithium (increases PTH levels in some patients, e.g., squamous cell carcinoma)
Hypercalcemia Hereditarya. Sarcoidosis-increased GI absorption of calcium b. Familial hypercalciuric hypercalcemia
Hypocalcemia less common causes5 . Pseudohypoparathyroidism-autosomal recessive disease causing congenital endorgan resistance to PTH (so PTH levels are actually high) ; also characterized by mental retardation and short metacarpal bones // Hypomagnesemia-results in decreased PTH secretion // Malabsorption-short bowel syndrome // Blood transfusion (with citrated blood)-Calcium binds to citrate. // Osteoblastic metastases // Hypoalbuminemia-but ionized fraction is normal so hypoalbuminemia is clinically irrelevant
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CLINICAL FEATURES OF HYPO/HYPERCALCEMIA

Question Answer
HypocalcemiaAsymptomatic // Rickets and Osteomalacia// Increased neuromuscular irritability//Basal ganglia calcifications//Cardiac manifestations
Hypocalcemia Increased neuromuscular irritabilitya. Numbness/tingling-circumoral, in fingers, in toes b. Tetany • Hyperactive deep tendon reflexes • Chvostek􀃩 sign-Tapping a facial nerve leads to a contraction (twitching) of facial muscles. • Trousseaus sign-Inflate BP cuff to a pressure higher than the patient's systolic BP for 3 minutes (occludes blood flow in forearm) . This elicits carpal spasms.c. Grand mal seizures
Hypocalcemia Cardiac Manifestationsa. Arrhythmias b. Prolonged QT interval on ECG-Hypocalcemia should always be in the differential diagnosis for a prolonged QT interval.
Hypercalcemial. "Stones" a. Nephrolithiasis b. Nephrocalcinosis 2. "Bones" a. Bone aches and pains b. Osteitis fibrosa cystica ("brown tumors") predisposes to pathologic fractures. 3. "Grunts and groans" a. Muscle pain and weakness b. Pancreatitis c. Peptic ulcer disease d. Gout e. Constipation 4. "Psychiatric overtones"-depression, fatigue, anorexia, sleep disturbances, anxiety, lethargy
Hypercalcemia Cardiac ManifestationsECG-shortened QT interval
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DIAGNOSIS OF HYPO/HYPERCALCEMIA

Question Answer
Hypocalcemia due to renal insufficiencyhigh serum phosphate // high PTH
Hypocalcemia due to hypoparathyroidismhigh serum phosphate // low PTH
Hypocalcemia due to primary vitamin D deficiencylow serum phosphate // high PTH
Hypocalcemia due to pseudohypoparathyroidismVery elevated PTH
Hypercalcemia due hyperparathyroidismPTH elevated in primary hyperparathyroidism // Urinary cAMP markedly elevated
Hypercalcemia due MalignancyPTH-related protein: elevated
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TREATMENT OF HYPO/HYPERCALCEMIA

Question Answer
Hypocalcemia acute symptomsIf symptomatic, provide emergency treatment with IV calcium gluconate. Make sure that magnesium is replaced.
Hypocalcemia for long term managementuse oral calcium supplements (calcium carbonate) and vitamin D.
Hypocalcemia due PTH deficiencyReplacement therapy with vitamin D (or calcitriol) plus a high oral calcium intake b. Thiazide diuretics-Lower urinary calcium, and prevent urolithiasis
Hypercalcemia initial step in managementIncrease urinary excretion.a. IV fluids (normal saline)-first step in management b. Diuretics (furosemide)-further inhibit calcium reabsorption
Hypercalcemia due malignancyInhibit bone resorption in patients with osteoclastic disease // a. Bisphosphonates (pamidronate) b. Calcitonin
Hypercalcemia due to vitamin D-related mechanisms (intoxication, granulomatous disorders) and multiple myelomaGive glucocorticoids
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