Differential Diagnosis
- Single most likely diagnosis
- Familial hypocalciuric hypercalcemia (FHH) or a similar condition causing secondary hyperparathyroidism due to urinary loss of calcium: The patient's elevated 24-hour urine calcium, normal to low serum calcium levels despite high PTH, and lack of parathyroid adenoma on imaging suggest a possible disorder of calcium handling in the kidneys.
- Other Likely diagnoses
- Idiopathic hypercalciuria: Characterized by elevated urinary calcium excretion without an identifiable cause, which could be contributing to the patient's secondary hyperparathyroidism.
- Renal calcium leak: A condition where the kidneys fail to reabsorb calcium properly, leading to excessive urinary calcium loss and potentially causing secondary hyperparathyroidism.
- Vitamin D deficiency or insufficiency: Although the patient's vitamin D levels are near normal, the decision to increase supplementation suggests that optimizing vitamin D status may help manage the patient's condition.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Hyperparathyroidism-jaw tumor syndrome: A rare genetic disorder that can cause primary hyperparathyroidism, but the lack of parathyroid adenoma and other symptoms makes this less likely.
- Malignancy-associated hypercalcemia: Although the patient's calcium levels are not markedly elevated, and there is no clear evidence of malignancy, this possibility should be considered, especially if the patient's condition worsens or other symptoms develop.
- Rare diagnoses
- Bartter syndrome: A rare genetic disorder affecting the kidneys' ability to reabsorb calcium, leading to excessive urinary calcium loss and potentially causing secondary hyperparathyroidism.
- Distal renal tubular acidosis (RTA): A condition characterized by impaired acid secretion and calcium reabsorption in the distal tubules, which could contribute to the patient's elevated urinary calcium excretion.