Hypercalcemia

Question 1

Accounts for 90% cases of hypercalcemia together with malignancies

Answer 1

Primary hyperparathyroidism

Question 2

Most common cause of primary hyperparathyroidism

Answer 2

Parathyroid adenoma

Question 3

Microscopic features of parathyroid adenoma

Answer 3

uniform, polygonal chief cells with small, centrally placed nuclei, no intervening adipose tissue

Question 4

See this description and decide

MEN 1/ MEN 2A / MEN 2B?
hyperparathyroidism, tumors of the pituitary and pancreas, gastric hypersecretion and peptic ulcer disease (Zollinger-Ellison syndrome).

Answer 4

MEN 1

Question 5

See this description and decide

MEN 1/ MEN 2A/ MEN 2B?
pheochromocytoma, medullary carcinoma of the thyroid, hyperparathyroidism

Answer 5

MEN 2A

Question 6

See this description and decide

MEN 1/ MEN 2A/ MEN 2B?
Medullary carcinoma of the thyroid, Pheochromocytoma, Mucosal neuromas, Ganglioneuromas, Marfanoid habitus

Answer 6

MEN 2B

Question 7

Mechanism of nephrolithiasis in hyperparathyroidism

Answer 7

Chronic PTH excess and hypercalcemia

Question 8

Mechanism of nephrocalcinosis in primary hyperparathyroidism

Answer 8

metastatic calcification of the basement membrane of the collecting duct tubules (CDT)

Question 9

Mechanism for pathologic fractures in primary hyperparathyroidism

Answer 9

PTH excess–>Loss of bone mass

Radiologic hallmark of PTH excess is subperiosteal resorption

Question 10

Name this morphologic feature of hyperparathyroidism

Answer 10

Brown tumor

Question 11

Mechanism of brown tumor formation in hyperparathyroidism

Answer 11

PTH excess–>increased osteoclast activity–>bone loss–> microfractures and secondary hemorrhages –>influx of macrophages , ingrowth of reparative fibrous tissue–>cystic brown tumor

Question 12

3 hallmark features of osteitis fibrosa cystica

Answer 12

increased bone cell activity + peritrabecular fibrosis + cystic brown tumors

Question 13

Cause of constipation in hypercalcemia

Answer 13

Hypercalcemia–> decreases the neuron membrane permeability to sodium ions–>decreasing the excitability–>hypotonicity of smooth muscle cells of the bowel

Question 14

Why is Vitamin D decreased in primary hyperparathyroidism?

Answer 14

Hypercalcemia decreases the synthesis of 1-α-hydroxylase in the proximal renal tubule, which decreases the synthesis of 1,25-(OH)2D

Question 15

Substance elaborated by squamous cell carcinoma of lung, renal cell carcinomas that causes hypercalcemia

Answer 15

PTHrP

Question 16

Pathogenesis of familial hypocalciuric hypercalcemia

Answer 16

inactivating mutation in a single allele of the CaSR–> increased secretion of PTH

Question 17

Mechanism for low urinary calcium excretion in familial hypocalciuric hypercalcemia

Answer 17

In the kidney, serum calcium concentrations are also detected (inappropriately) as low by the mutated CaSR, and calcium is retained

Question 18

Mechanism of hypercalcemia in sarcoidosis

Answer 18

excess 1,25(OH)2D is synthesized in macrophages in the granulomas by converting 25(OH)D to 1,25(OH)2D at an increased rate.