Patient's question:
How should hypervitaminosis D be treated?Doctor's answer:
Vitamin D-resistant rickets (vitamin D-resistant rickets) has two types: hypophosphatemic and hypocalcemic.The more common hypophosphatemic vitamin D-resistant rickets follows the principle of preventing bone deformities and, as much as possible, increasing blood phosphorus levels to maintain them above 0.97 mmol/L (3 mg/dL), which is beneficial for bone calcification. It is also necessary to maintain normal growth rates while avoiding the occurrence of hyperuricemia and hypercalcemia caused by vitamin D toxicity. Below is a brief description of the advantages and disadvantages of various measures:
① Simple oral phosphate supplementation: To raise blood phosphorus levels to normal, phosphate preparations are often required. Typically, 18 g of sodium dihydrophosphate and 145 g of disodium hydrogen phosphate are dissolved in water to make 1000 mL. The dosage is 15–20 mL per time, five times daily. This provides 2 g of phosphorus (elemental phosphorus) per day. Phosphate preparations have an unpleasant taste and are prone to causing diarrhea. To better promote phosphorus absorption in the intestines, vitamin D or DHT should be administered concurrently.
② Combined use of phosphate and vitamin D: The dosage of vitamin D is 10,000–50,000 IU/day, with a maximum of 100,000 IU/day. Vitamin D is easily stored in body fat, and symptoms of toxicity may not appear until significant accumulation occurs, making it prone to causing toxicity. DHT is a vitamin D-like preparation that exerts vitamin D-like effects after hydroxylation in the body and is less likely to accumulate in body fat, reducing the risk of toxicity and being safer. Initially, a dosage close to 2 mg/day is required for 2–4 weeks, followed by a maintenance dose of 0.5–1.5 mg/day to control the condition. After treatment, plasma alkaline phosphatase levels return to normal, but blood phosphorus remains low, so phosphate preparations should be taken concurrently. Among phosphate preparations, potassium phosphate is more palatable and may cause hypocalcemia if taken alone. If 0.75–1 μg/day of 1,25(OH)2D3 is administered along with phosphate preparations, the therapeutic effect is even better.