What is Hypervitaminosis D?
Hypervitaminosis D (vitamin D intoxication) is a condition caused by both the direct toxic effect of the drug on the cell membranes and the increased concentration of calcium salts in the blood, which are deposited in the walls of the vessels of the internal organs, primarily the kidneys and the heart. Hypervitaminosis D occurs when an overdose of this vitamin or individual hypersensitivity to it. They distinguish acute and chronic intoxication with vitamin D.
Causes of Hypervitaminosis D
The use of large doses of vitamin D for treatment or prevention; usually the total dose is above 1 million ME. Sometimes hypervitaminosis and cause small doses (4-8 thousand ME), which is explained by hypersensitivity to vitamin D.
Pathogenesis during Hypervitaminosis D
The main is the toxic effect of vitamin D on cell membranes, metabolic disorders with the development of hypercalcemia and hypercalciuria, hyperphosphaturia, acidosis, calcification of tissues and internal organs.
Symptoms of Hypervitaminosis D
Acute intoxication with vitamin D often develops in children of the first half of life with a massive intake of vitamin D for a relatively short period of time (2-3 weeks) or individual hypersensitivity to vitamin D. At the same time, there are signs of neurotoxicosis or intestinal toxicosis: the appetite is sharply reduced, the child is thirsty, vomiting often occurs, body weight quickly decreases, dehydration develops, constipation appears (unstable and loose stools are possible). In some children, short-term loss of consciousness is recorded, tonic-clonic convulsions are possible.
Chronic intoxication with vitamin D occurs on the background of prolonged (6-8 months or more) use of the drug in moderate, but still exceeding the physiological need doses. The clinical picture is less distinct and includes irritability, poor sleep, weakness, pain in the joints, a gradual increase in dystrophy, premature closure of a large fontan, changes in the cardiovascular and urinary systems.
Diagnosis of Hypervitaminosis D
The diagnosis is based on anamnesis, clinical symptoms, a positive sample of Sulkovich, the detection of hypercalcemia and hypercalciuria, a decrease in alkaline phosphatase activity.
Differential diagnosis should be carried out with hyperparathyroidism, idiopathic calcification.
Laboratory criteria for hypervitaminosis D: an increase in the concentration of phosphorus and calcium in the blood and urine, a compensatory increase in the concentration of calcitonin and a decrease in parathyroid hormone.
Treatment of Hypervitaminosis D
Treatment of hypervitaminosis D is carried out in the hospital. Eliminate vitamin D and insolation, prescribe vitamins A and E, infusion therapy in combination with diuretics (furosemide). In severe cases, prednisone is prescribed in a short course.
The forecast is serious. The most unfavorable is the development of nephrocalcinosis and chronic pyelonephritis with the subsequent development of chronic renal failure.
Prevention of Hypervitaminosis D
In each case of treating rickets with vitamin D, it is advisable to monitor the excretion of calcium in the urine using the Sulkovich test (Sulkovich’s reagent — 2.5 g of oxalic acid, 2.5 g of ammonium sulfate and 5 ml of glacial acetic acid is dissolved in distilled water and the volume is adjusted to 150 ml (10 drops of Sulkovich’s reagent are added to 10 drops of urine. With hypercalciuria, significant turbidity appears). Avoid prescribing vitamin B in shock doses.