A 34-year-old man with type 1 diabetes mellitus visits the office because he has been experiencing achy pain in his shoulders, elbows, and thighs for several months. The patient was diagnosed with diabetes 15 years ago and has struggled to keep it under control. He currently receives multiple insulin injections per day. The vital signs are within normal ranges. A physical exam reveals mild pedal edema. Serum creatinine has increased to 2.2 mg/dL from 1.6 mg/dL six months ago. Additional tests reveal low serum calcium and elevated parathyroid hormone levels. Which of the following enzymatic steps is most likely causing this patient's current symptoms?

Question

Quizplus · Accepted Answer

Eductional Objective: The conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D is impaired in chronic kidney disease. Furthermore, phosphate retention and hypocalcemia result from glomerular and tubular dysfunction. This causes a compensatory increase in parathyroid hormone (secondary hyperparathyroidism), which can cause weakness, muscle and joint pain, defective bone mineralization, and an increased risk of fracture.

A 34-Year-Old Man with Type 1 Diabetes Mellitus Visits the Office