In a patient with chronic renal failure and type 2 diabetes, which laboratory finding is most likely to increase?

• A. Calcium
• B. Phosphate
• C. Parathyroid hormone
• D. Hemoglobin

Answer: (B)

In patients with chronic renal failure, there is a marked impairment in the kidneys' ability to excrete phosphate. Normally, the kidneys help regulate phosphate levels by excreting excess amounts. As renal function declines, phosphate retention occurs, leading to elevated serum phosphate levels. This is exacerbated in patients with diabetes, where metabolic disturbances can further affect kidney function.

The increase in phosphate levels can result from several factors, including reduced glomerular filtration rate (GFR), which is a hallmark of chronic renal failure. As phosphate accumulates, it can lead to secondary changes such as hyperparathyroidism, as the parathyroid glands respond to relatively low calcium levels and elevate parathyroid hormone production to increase calcium and decrease phosphate levels in the body.

This situation often leads to complications like vascular calcifications and bone disease due to shifting mineral balance. Therefore, in the context of chronic renal failure combined with type 2 diabetes, the most likely laboratory finding to be increased is phosphate.