Differential Diagnosis for Hypocalcemia
Single Most Likely Diagnosis
- Vitamin D deficiency: This is often the most common cause of hypocalcemia, especially in populations with limited sun exposure, inadequate dietary intake, or malabsorption. Vitamin D plays a crucial role in calcium absorption from the gut.
Other Likely Diagnoses
- Hypoparathyroidism: A condition where the parathyroid glands are underactive or have been removed, leading to insufficient production of parathyroid hormone (PTH), which is essential for maintaining normal calcium levels.
- Chronic Kidney Disease (CKD): CKD can lead to hypocalcemia due to impaired activation of vitamin D, reduced calcium absorption, and increased phosphate levels, which can lower calcium levels.
- Magnesium deficiency: Magnesium is important for the release of PTH and the activation of vitamin D. A deficiency can lead to hypocalcemia that is resistant to treatment with calcium and vitamin D alone.
Do Not Miss Diagnoses
- Medication-induced hypocalcemia: Certain medications like bisphosphonates, denosumab, and cinacalcet can cause hypocalcemia. Recognizing and managing these causes is crucial to prevent severe hypocalcemia.
- Hungry bone syndrome: This condition occurs after parathyroid surgery in patients with hyperparathyroidism, where the bones, which were previously under-resorbed, start to take up a lot of calcium, leading to hypocalcemia.
Rare Diagnoses
- Pseudohypoparathyroidism: A rare genetic disorder characterized by resistance to PTH, leading to hypocalcemia and hyperphosphatemia.
- Barter syndrome and other renal tubular disorders: These are rare genetic disorders affecting the kidneys' ability to reabsorb calcium and magnesium, leading to hypocalcemia among other electrolyte imbalances.
- Osteoblastic bone metastases: Certain types of cancer, like prostate cancer, can metastasize to bone and cause an osteoblastic reaction, leading to increased bone density and hypocalcemia due to increased calcium deposition in bone.