hypocalcemia

Question 1

Elemental CA

• Calcium carbonate
• Calcium Citrate
• Calcium gluconate

Answer 1

• Calcium carbonate
  
  • ​40%
• Calcium Citrate
  
  • ​20%
• Calcium gluconate
  
  • 10 %

Question 2

Hypocalcemia labs

• Serum PTH concentrations
• Magnesium
• Phosphate
• Vitamin D metabolites
• Other

Answer 2

**PTH **Hypocalcemia potent stimulus of PTH secretion / normal serum PTH level evidence of hypoparathyroidism. ■ Serum PTH is reduced or inappropriately normal in patients with hypoparathyroidism.

• *Serum PTH is elevated** in patients with acute or chronic kidney disease, vitamin D deficiency, and pseudohypoparathyroidism.
• *Serum PTH is typically normal or low in patients** with hypomagnesemia or autosomal dominant hypocalcemia, a rare disorder characterized by an activating mutation in the calcium-sensing receptor gene.

Hypomagnesemia: below 0.8 meq/L / Hypocalcemia should resolve within minutes or hours after restoration

Hyperphosphatmia: in absence of kidney disease or increased tissue breakdown, virtually diagnostic of either hypoparathyroidism (PTH deficiency) or pseudohypoparathyroidism (PTH resistance). Loss of the stimulatory effect of PTH on urinary phosphate excretion

Hypophosphatemia: indicates either excess PTH secretion, which in the context of hypocalcemia means secondary hyperparathyroidism

Vitamin D deficiency increases PTH secretion by causing hypocalcemia
■ A low serum 25OHD in pt with hypocalcemia and hypophosphatemia usually indicates that vitamin D intake or absorption is low
■ The combination of normal or low serum 25OHD concentration and low serum 1,25-dihydroxyvitamin D concentration, with high-normal or elevated serum phosphate, indicates the presence of chronic kidney disease. Chronic kidney disease is the only condition in which hypocalcemia and secondary hyperparathyroidism are not associated with low or low-normal serum phosphate (as a result of the inability of the diseased kidney to respond to the high PTH).
■The combination of normal or low serum 25OHD concentration, low serum 1,25-dihydroxyvitamin D concentration, and low serum phosphate suggests the presence of vitamin D-dependent rickets, type 1 (renal 1-alpha-hydroxylase deficiency), also called pseudo-vitamin D deficient rickets.

■Hereditary vitamin D-resistant rickets (also called vitamin D-dependent rickets, type 2) presents in early childhood and is associated with a defect in the vitamin D receptor. It should be suspected in hypocalcemic patients if serum phosphate is low and serum 1,25-dihydroxyvitamin D concentrations are high. (See “Etiology and treatment of calcipenic rickets in children”, section on ‘Hereditary vitamin D resistant rickets’.)

■An elevated alkaline phosphatase is common in osteomalacia (as a result of severe vitamin D deficiency and secondary hyperparathyroidism) and can occur with osteoblastic bone metastases, which can cause hypocalcemia due to rapid deposition of calcium in bone metastases [1].

■Serum amylase is elevated in acute pancreatitis but only slightly in chronic pancreatitis.
■Low urinary calcium occurs in patients with untreated hypoparathyroidism or vitamin D deficiency.
■Assessment of urinary magnesium may be helpful in individuals with hypomagnesemia. In this setting, an elevated value is consistent with renal losses.