Which of the following is a common cause of a calcium renal stone?

• A. Dehydration due to excessive sweating
• B. Hypokalemia
• C. Hyperparathyroidism
• D. Low dietary calcium intake

Answer: (C)

Verified step by step guidance

1. Understand the context: Calcium renal stones, also known as kidney stones, are solid masses formed in the kidneys due to the crystallization of calcium and other substances. Identifying the cause requires knowledge of physiological processes and risk factors.
2. Review the options: Dehydration due to excessive sweating can lead to concentrated urine, increasing the risk of stone formation. Hypokalemia (low potassium levels) is not directly linked to calcium stone formation. Hyperparathyroidism, a condition where the parathyroid glands produce excess parathyroid hormone, can increase calcium levels in the blood and urine, promoting stone formation. Low dietary calcium intake can paradoxically increase calcium stone risk by allowing more oxalate absorption in the gut.
3. Focus on hyperparathyroidism: Excess parathyroid hormone leads to increased calcium release from bones, enhanced calcium absorption in the intestines, and reduced calcium excretion by the kidneys. This results in hypercalciuria (high calcium levels in urine), a major risk factor for calcium stone formation.
4. Consider dehydration: Dehydration due to excessive sweating reduces urine volume, making it more concentrated and increasing the likelihood of calcium and other substances crystallizing into stones.
5. Conclude: Hyperparathyroidism is the most direct and common cause of calcium renal stones among the options provided, as it directly affects calcium metabolism and excretion.