Vitamin overdosage

Table 2 Notable symptoms reported with chronic and acute vitamin overdosage (SEDA-13, 345) (6,10)...

OH-D3 may prove to be helpful in anticipating overdosage. However, systematic studies which correlate vitamin D dosage, 25-OH-D3 serum concentrations, and serum calcium in patients such as these, have not yet been reported. 

VII.a.2.2. Treatment. Treatment of established vitamin D deficiency requires much larger doses of vitamin D, such as calciferol tablets of 1 mg (40,000 units) daily. Newer but more expensive preparations such as alfa-calcidol and calcitriol are very effective, and are particularly valuable in patients with renal failure who are unable to hydroxylate calciferol. Patients treated with pharmacological doses of vitamin D preparations must be monitored by checking serum calcium at regular intervals because of the risk of inducing hypercalcaemia. This should always be suspected if patients develop thirst, nausea or vomiting. The newer hydroxylated preparations have a shorter effective half-life, and therefore problems of overdosage are quicker to resolve once identified. 

The water-soluble salt of vitamin K3 (menadione) should never be used in therapeutics. It is particularly ineffective in the treatment of warfarin overdosage. Vitamin K deficiency frequently occurs in hospitalized patients in intensive care units because of poor diet, parenteral nutrition, recent surgery, multiple antibiotic therapy, and uremia. Severe hepatic failure results in diminished protein synthesis and a hemorrhagic diathesis that is unresponsive to vitamin K. 

Another argument against simple vitamin D overdosage or hypersensitivity in idiopathic hypercalcemia is the response to withdrawal of all vitamin D. In even the grossest cases of vitamin D poisoning in... 

Schrauzer GN, Ishmael D, Kiefer GW. Some aspects of current vitamin C usage diminished high-altitude resistance following overdosage. Ann NY Acad Sci 1975 258 377-81. 

The characteristic features of chronic intoxication are deposition of calcium salts in various tissues. A followup study of 24 children with vitamin D intoxication (13 900-200 000 lU/day) for up to 13 years showed that 23% of the patients had permanent damage. The severity of renal, neurological, and digestive symptoms was related to the daily dose, but the final consequences depended on the duration of overdosage (7). Vitamin D intoxication has also been seen after so-called Stoss prophylaxis in children, that is the use of single very... 

Kernicterus can occur in small and premature babies, even after small doses of vitamin K, probably because of immature liver function. In its 1997 clinical practice guidelines, the Canadian Paediatric Society recommended that, in order to prevent haemorrhagic disease of the newborn, phytomenadione be given as a single intramuscular injection to all newborns within 6 hours of birth, in a dose of 1 mg for infants with a birth weight of more than 1500 g and half this dose for smaller infants. The dose is crucial, since overdosage carries a serious risk of kernicterus, especially in premature infants. There is only a remote possibility that this treatment might increase the risk of childhood cancer. 

There is widespread and easy availability of high-dose single and multiple vitamin formulations, often presented as food supplements. This creates a potential for chronic or sporadic intake of high doses of vitamins and the occurrence of unanticipated adverse effects (11,12). The cases often involve children, who may be specially vulnerable to the effects of overdosage. The Canadian Paediatric Society s Nutrition Committee in 1990 issued a warning to physicians, based on an estimate that as many as 10% of healthy Canadian children were being exposed to vitamin polypharmacy and a substantial risk of accidental overdose (13). 

Overdosage of vitamins A and D produces hypervita-minosis. In recognition of this, the FDA has ruled that vitamin A in doses greater than 10,000 lU and vitamin D in doses greater than 400 lU should be available on a prescription-only basis and that all products containing quantities of a vitamin in excess of 150% of its RDA be classified as a drug. Hypervitaminosis D was discussed in Chapter 37 vitamin A toxicosis is discussed below. The toxicity of high doses of vitamin Be is also covered later in the chapter. 

Vitamin requirements for ESKD patients receiving dialysis differ from those of a healthy person because of dietary modifications, kidney dysfunction, and dialysis therapy. The plasma concentrations of vitamins A and E are elevated in ESKD, while those of the water-soluble vitamins (81,82,8g, 812, niacin, pantothenic acid, folic acid, biotin, and vitamin C) tend to be low in this population, in large part due to the fact that many are dialyzable. The goal for vitamin supplementation in this population should be to prevent subclinical and frank deficiency and to avoid pathology from overdosage. Special vitamin supplements have been formulated for the dialysis population, which primarily include 8 vitamins with C and folic acid. 

In the case of Vitamin K-deficency owing to bile obstruction, which has lowered the value for prothrombin complex, vitamin K1 is administered intravenously. In moderate vitamin K-deficiency induced by therapy with antibiotics or diarrhoeas of long duration, oral vitamin K therapy is needed. Prophylactically vitamin K is used for treatment of haemorrhage in the newborn and therapeutically in cases of overdosage of warfarin-type anticoagulants. 

A condition similar to vitamin A (retinol) overdosage may occur if acitretin or isotretinoin are given with vitamin A. 

Combined treatment with isotretinoin and vitamin A may result in a condition similar to overdosage with vitamin A. Concurrent use should therefore be avoided or very closely monitored because changes in bone structure can occur, including premature fusion ofthe epiphyseal discs in children. ... 

Vitamin D Vitamin D is produced when ultraviolet light (UV) shines on the skin and triggers the conversion of a steroid known as ergosterol to vitamin D. Its major role is to help the body use calcium, and a deficiency causes rickets in children, the same condition caused by calcium deficiency. Vitamin D supplements are rarely needed, except by those who are almost never exposed to the sun. Both vitamin A and vitamin D are essential to normal growth and development. Overdosage of vitamin D can have serious consequences, however. Calcium deposits can form in the kidney, lungs, or tympanic membrane of the ear (leading to deafness). Infants and small children are especially susceptible to vitamin D toxicity. 

In regard to the possibility of an overdosage of vitamin D, Bedin (1947) reported that vitamin A can prevent toxic symptoms caused by high doses of vitamin D. The vitamin A administration, as mentioned in Section II, 8, may be beneficial for this and for other reasons. At therapeutic levels, vitamin A increases the good effects of vitamin D. 

Recently MacIntyre (1959) pointed to the striking similarity of symptoms and biochemical aspects of magnesium deficiency and hypervitamino-sis D, a fact that certainly is of interest in respect to the data mentioned in Section II, 9 on the role of overdosage of vitamin D. 

Overdosage with vitamin D can cause hypercalcaemia. Oversensitivity to vitamin D is thought to be the cause of two hyper-calcaemic conditions, sarcoidosis and idiopathic hypercalcaemia of infancy. 

Adults should also E)e warned about taking meissive doses of vitamin D (as well as ab ut taking meissive doses of vitamin A) over a long period of time unless it is under the supervision of a physician or nutritionist Even moderate overdosage of vitamin D is not wise for the elderly. 

Vitamin K, preparations are preferred for the treatment of such medical conditions as liver disease, severe malabsorption syndromes, and anticoagulant overdosage. 

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