Hypervitaminosis D

The toxic effect of high doses of vitamin D has been known since 1929. Hypervitaminosis can occur with an unreasonable prescription of the drug without taking into account individual sensitivity to "shock" doses. Individual reactions to the introduction of vitamin D can be due to both genetic factors and changes that occurred in the child's body under the influence of environmental factors.

An overdose of vitamin D has on the child's body both direct and indirect toxic effects - through the disruption of phosphorus-calcium homeostasis and the development of hypercalcemia. Excessive intake of vitamin D in the blood leads to a sharp increase in calcium absorption in the intestine and causes bone resorption.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]

Symptoms of hypervitaminosis D

Symptoms of hypervitaminosis D are well studied and look like acute toxicosis or chronic intoxication (the differences depend on the child's age, duration of vitamin D administration). Acute toxicosis often occurs in children of the first half of life, the appointment of large doses of vitamin D in a short period of time. In the second half of the year, the development of chronic intoxication is possible (with prolonged intake of small doses of vitamin D). The main symptoms: anorexia, hypotrophy, asthenia, nausea, vomiting, developmental delay, constipation, polyuria, polydipsia, dehydration and seizures. The degree of damage to the nervous system varies from mild inhibition to severe coma.

• There are three degrees of hypercalcemia:
• the first degree - the calcium content in the blood is stable at the upper limit of the norm, it is intensively excreted in the urine (Sulkovich's reaction +++), in the clinical picture - moderate toxicosis, polyuria, polydipsia, weight loss;
• the second degree - the calcium content in the blood is higher than normal, but does not exceed 12 mg%, Sulkovich's reaction +++ or ++++, in the clinical picture - pronounced toxicosis, polyuria. Dystrophy;
• the third degree - the content of calcium in the blood more than 12 mg%, severe toxicosis and mandatory damage to the kidneys. 

Intensity of cardiovascular damage varies from small functional disorders to severe myocarditis with circulatory failure. With liver damage, the activity of serum transaminases can be increased, dysproteinemia is possible, the content of cholesterol in the blood is increased, the ratio of α- and β-lipoproteins is disrupted; describes pathological types of glycemic curves. Kidney damage varies from small dysuric phenomena to acute renal failure; characteristic leukocyturia, minor hematuria and proteinuria; often secondary infection and the development of pyelonephritis; nephrocalcinosis: oxalate-calcinate urolithiasis. With the progression of these diseases, chronic renal failure develops.

The defeat of the respiratory system, gastrointestinal tract are rare.

Diagnosis of hypervitaminosis D

The diagnosis of hypervitaminosis D is put on detection of a complex of biochemical changes (hypercalciuria, hypercalcemia, hypophosphatemia and hyperphosphaturia, acidosis possible). Radiographically, it is possible to establish intensive lime deposition in the epiphyseal zones of the tubular bones and an increased porosity of the diaphysis. The skull bones are compacted. The big fontanel closes early. Important data is an anamnesis about the intake of vitamin D, especially in high doses.

When making the diagnosis, Sulkovich's trial is widely used. With hypercalciuria, a mixture of the Sulkovich reagent with a double amount of urine immediately gives a gross turbidity, whereas in healthy children, mild milk-like opacification appears immediately or after a few seconds.

However, the sample is not a reliable test, so in doubtful cases it is necessary to check the calcium and phosphorus content in the blood simultaneously.

After the hypervitaminosis A, nephropathies often develop: chronic pyelonephritis, interstitial nephritis, tubulopagia. 

[12], [13], [14], [15], [16], [17], [18]

Tactics of management of children with hypervitaminosis D

Hypervitaminosis D can take an atypical course. If there is a suspicion of intoxication caused by vitamin D preparations, it is necessary immediately to cancel the drug and stop the introduction of calcium salts. Exclude from the diet of the child products rich in calcium: whole cow milk, kefir, cottage cheese, if possible, replacing them with expressed breast milk (fractional feeding). Assign a generous drink of tea, 5% glucose solution and prescribe vitamin A for 5000-10 000 ME (2 drops 2-3 times a day, vitamins B, E. Simultaneously, you should make a Sulkovich test, examine the calcium content in the patient's blood serum. Toxicosis with vitamin D is treated in a hospital environment, in addition to the above-mentioned measures, drip infusion of liquids (5% pacit glucose, 0.9% sodium chloride solution) is prescribed from the calculation of the daily requirement.

At the expressed intoxication are shown glucocorticoids, promoting deducing of a calcium with urine. Prednisolone is prescribed at 1.0-1.5 mg per 1 kg of body weight per day for 8-12 days.

A properly organized general hygiene regime, aerotherapy, massage, therapeutic gymnastics, individual care is important. As the symptoms of intoxication disappear, the patient's diet can be expanded.

Children who have suffered intoxication with vitamin D, should be observed in the clinic for 2-3 years. Periodically, it is necessary to examine urine analysis and functional tests of the kidneys, pay attention to the condition of the cardiovascular system, monitor electrocardiographic parameters.

How to prevent hypervitaminosis D?

Prevention of hypervitaminosis D is closely related to the rational prevention of rickets. When prescribing any vitamin D preparations, it is important to remember about its possible toxic effect, so the dose should be determined as accurately as possible, summarizing all sources of vitamin D intake. The development of hypervitaminosis inhibits simultaneous administration of vitamins A and B.

Carrying out prevention, it is important to take into account the individual sensitivity of the child to vitamin D, for clarification, you should carefully collect the anamnesis and systematically monitor the child's condition. Premature and fed on the artificial and mixed feeding of children during the period of vitamin D administration regularly (once a week) make a Sulkovich test to detect the first signs of intoxication.