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27 Cards in this Set
- Front
- Back
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total body calcium
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1 kg; most is in bones. very tiny amt is extracellular, most of which is bound.
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PTH and calcium relationship
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PTH increases serum Ca and high serum Ca provides negative feedback of PTH.
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PTH acts at these sites
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bone, kidney, gut
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PTH @bone
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PTH increases bone resorption by activating osteoclasts to release Ca from bone
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PTH @kidney
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PTH increases tubular Ca reabsorption
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PTH @gut
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PTH indirectly (by activating vit D) increases dietary Ca absorption
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CaSR
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calcium-sensing receptor on PT gland , where it binds to provide neg feedback
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indirect effects of PTH on Ca
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PTH increases αhydroxylation of vitD, promoting Ca absorption at gut and kidney
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direct effects of PTH on Ca
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↑bone resorption and ↑ Ca reabsorption at the kidney
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calcitonin
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Directly inhibits gut absorption of Ca, Inhibits Ca reabsorption at the kidney, Inhibits bone resorption
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phosphorous reabsorption
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Occurs in Renal proximal tubular cell, where it is reabosrbed by NaPT2a cotransporter; increased PTH removes this transporter from membrane, so more Phos is excreted
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signs and sx of hypercalcemia
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serendipity, stones, bones, groans, and psychiatric overtones.
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hypercalcemic pts
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Most are asx; nephrolithiasis, bone pain, abd pain, NV, lethargy, depression, anxiety, stupor, hypotonia, hyporeflexia, hypertension, bradycardia, calcification of mets
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hypercalcemia acute crisis
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anorexia, polyuria, dehydration, impaired mentation, immobilization, hypercalcemia
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causes of hypercalcemia
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primary/familial/tertiary parahyperthyroidism, mccune albright, vitD intoxication, SCC, meds like lithium, thiazide
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primary hyperparathyroidism
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Most common cause of hypercalcemia in outpatients. age 30+, females > males, most are asx
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primary hyperparathyroidism labs
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Mildly high Ca/PTH, mildly low Phos; 24hr urine Ca is high
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primary hyperparathyroidism causes
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adenoma > hyperplasia > carcinoma. surgery for most.
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tertiary hyperparathyroidism
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CKD pts w/ low 1,25 vitD and low Ca >> overproduction of PTH. Tx surgery.
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FHH
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inactivating mutation of CaSR; **hypocalciuria; test Ca of first-degree relative
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HPTH-jaw tumor syndrome
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mutation sin HRPT2 tumor suppressor
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MEN1
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3 P's; mutation in MEN1 tumor suppressor
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MEN2
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MTC, pheo, hyperpara, mutation in RET
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McCune Albright syndrome
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apparent PTH "excess" that is really a mutation >> constituently active G protein
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McCune Albright sx
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cafe au lait lesions w/ jagged coast of main border that respect midline; precocious puberty, high Ca, high 1,25 D, high alk phos, normla PTH
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endocrine causes of mild hypercalcemia
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hyperthyroidism, adrenal insufficiency, pheo, vipoma
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meds that cause mild hypercalcemia
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vitD OD, milk-alkali syndrome, lithium, thiazide diuretics
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