Parathyroid gland

Question 1

What lab changes would be expected in primary hyperparathyroidism? (PTH, [Ca²⁺], [P_i], and Vit D)

Answer 1

Caused by excessive secretion of PTH from the parathyroid gland

elevated PTH, Ca²⁺, and Vit D

decreased P_i

Question 2

What lab changes would be expected in secondary hyperparathyroidism due to renal failure? (PTH, [Ca²⁺], [P_i], and Vit D)

Answer 2

Caused by low [Ca²⁺] due to renal loss

elevated PTH and P_i (lack of renal excretion)

decreased Ca²⁺ and Vit D (activated in the kidney)

Question 3

What lab changes would be expected in secondary hyperparathyroidism due to vitamin D deficiency? (PTH, [Ca²⁺], [P_i], and Vit D)

Answer 3

elevated PTH

decreased Ca²⁺ (loss of absorption in the intestine), P_i (loss of absorption in the intestine and reabsorption in kidney), and Vit D

*Different from due to renal failure as P_i absorption in the intestine is mediated by Vit D and therefore P_i will be low*

Question 4

What lab changes would be expected in hypoparathyroidism? (PTH, [Ca2+], [Pi], and Vit D)

Answer 4

elevated P_i

decreased PTH, Ca²⁺, and Vit D

Question 5

What lab changes would be expected in pseudohypoparathyroidism? (PTH, [Ca²⁺], [P_i], and Vit D)

Answer 5

Caused by defect in the G_s subunit of PTH receptor in the kidneys and bone (decreased osteoclast activation, decreased renal Ca²⁺ reabsorption, decreased renal activation of Vit D, and unihibited renal P_i reabsorption)

elevated PTH and [P_i]

decreased [Ca²⁺] and Vit D

Question 6

What lab changes would be expected in certain malignancies? (PTH, [Ca²⁺], [P_i], and Vit D)

Answer 6

caused by production of PTH-related peptide (a PTH analog) by certain tumors

increased [Ca²⁺]

decreased PTH, [P_i], and Vit D

Question 7

What lab changes would be expected in FHH? (PTH, [Ca2+] (serum and urinary), [Pi], and Vit D)

Answer 7

Caused by mutation in CaSR in parathyroid gland and kidney

elevated serum [Ca²⁺] (possibly mildly elevated PTH)

decreased urinary [Ca²⁺]

others relatively normal