A 50-year-old man has had a nonhealing ulcer on the bottom of his foot for 2 months. On examination, the 2-cm ulcer overlies the right first metatarsal head. There is reduced sensation to pinprick in his feet. His visual acuity is reduced bilaterally. Laboratory studies show serum creatinine is 2.9 mg/dL. Which of the following laboratory test findings is he most likely to have?

Correct Answer: A

Rationale: Complications of diabetes mellitus are described in this man: vascular disease, neuropathy, nephropathy, and retinopathy. Hyperglycemia exceeds the capacity of renal tubular reabsorption, so glucose appears in the urine. The other listed findings involve organs that are not typically involved in diabetes mellitus: liver disease with decreased albumin synthesis, hyperaldosteronemia with hypokalemia, decreased marrow function with leukopenia, exocrine pancreatic disease with steatorrhea.

Correct Answer: D

Rationale: Ca2+ binds troponin, exposes actin sites, is stored in SR; ATP hydrolysis is by myosin ATPase, not Ca2+.

Correct Answer: D

Rationale: All are true: unique structure, plateau phase (Ca2+ influx), dual Ca2+ sources.

Correct Answer: C

Rationale: Type O has anti-A and anti-B, as it lacks A/B antigens.

Correct Answer: C

Rationale: C1 binds antigen-antibody complexes, initiating classic complement.