calcium phosphorus pth

Question 1

normal calcium/phosphate homeostasis

Answer 1

-vitamin D -> 25-OH vit D -> 1-25-(OH)2 vit D -> calcium absorption from the gut -> maintenance of Ca2+ homeostasis

Question 2

bone manifestation of CKD/renal osteodystrophy

Answer 2

-hypocalcemia:
-impaired osteoid mineralization by osteoblasts
-osteomalacia- accumulation of unmineralized bone matrix
-hyperparathyroidism- increased osteoclast activity/calcium resorption from bone
-osteitis fibrosa cystica:
-abnormal osteoid
-bone marrow fibrosis
-formation of cysts- +/- hemorrhage, brown tumors
-osteomalacia + osteitis fibrosa cystica +/- osteoporosis = renal osteodystrophy

Question 3

causes of hypocalcemia

Answer 3

-Malabsorption
-Vitamin D deficiency
-Chronic kidney disease
-Loop diuretic use
-Hypoparathyroidism
-Pancreatitis
-Septic shock
-Hyperphosphatemia

Question 4

causes of hypercalcemia

Answer 4

-Milk-alkali syndrome
-Vitamin D toxicity
-Hyperparathyroidism
-Pheochromocytoma
-Thyrotoxicosis
-PTH producing tumor
-Multiple myeloma
-Lymphoma
-Thiazide diuretic use
-Lithium use