Electrolyte - hope08

[ArchivalUser]

A 69-year-old man comes to clinic complaining of chronic pain in his joints. He is well known to the clinic, where he is followed for hypertension, diabetes, and renal failure requiring hemodialysis three times per week. While he is compliant with dialysis, he often fails to take his medications, and tends to pick and choose which pills he takes. During the patient™s physical examination, multiple small, firm subcutaneous nodules are noted on his forearms, chest, and back. Additionally, radiographs taken as part of the patient™s workup reveal diffuse calcifications in the arteries, joints, and soft tissue. The pattern is described in the radiologist™s report as a œmetastatic calcification pattern. Which of the following is the most likely underlying electrolyte abnormality?

A. Hyperkalemia
B. Hyperphosphatemia
C. Hypocalcemia
D. Hypokalemia
E. Hypophosphatemia

[ArchivalUser]

B?

[ArchivalUser]

D. Hypokalemia ?

[ArchivalUser]

B?

[ArchivalUser]

The correct answer is B. Dialysis patients need to take phosphate binders. Phosphate is normally cleared by the kidney, but is poorly filtered by hemodialysis. Long-standing hyperphosphatemia can result in calcium-phosphate aggregations, which diffusely precipitate, a process known as metastatic calcification. Further, such patients are at risk for significant renal osteodystrophy. The homeostatic response to the elevated PTH levels and calcium-phosphate aggregations is to release more calcium from bone. As such, calcium levels are usually normal, not low (choice C). As the kidney no longer clears phosphate, and dialysis does not remove the phosphate, hypophosphatemia (choice E) is unlikely.