Case-control study of the role of nutritional rickets in the risk of developing pneumonia in Ethiopian children

A comparison of calcium, vitamin D, or both for nutritional rickets in Nigerian children

BACKGROUND

Nutritional rickets remains prevalent in many tropical countries despite the fact that such countries have ample sunlight. Some postulate that a deficiency of dietary calcium, rather than vitamin D, is often responsible for rickets after infancy.

METHODS

We enrolled 123 Nigerian children (median age, 46 months) with rickets in a randomized, double-blind, controlled trial of 24 weeks of treatment with vitamin D (600,000 U intramuscularly at enrollment and at 12 weeks), calcium (1000 mg daily), or a combination of vitamin D and calcium. We compared the calcium intake of the children at enrollment with that of control children without rickets who were matched for sex, age, and weight. We measured serum calcium and alkaline phosphatase and used a 10-point radiographic score to assess the response to treatment at 24 weeks.

RESULTS

The daily dietary calcium intake was low in the children with rickets and the control children (median, 203 mg and 196 mg, respectively; P=0.64). Treatment produced a smaller increase in the mean (+/-SD) serum calcium concentration in the vitamin D group (from 7.8+/-0.8 mg per deciliter [2.0+/-0.2 mmol per liter] at base line to 8.3+/-0.7 mg per deciliter [2.1+/-0.2 mmol per liter] at 24 weeks) than in the calcium group (from 7.5+/-0.8 [1.9+/-0.2 mmol per liter] to 9.0+/-0.6 mg per deciliter [2.2+/-0.2 mmol per liter], P<0.001) or the combination-therapy group (from 7.7+/-1.0 [1.9+/-0.25 mmol per liter] to 9.1+/-0.6 mg per deciliter [2.3+/-0.2 mmol per liter], P<0.001). A greater proportion of children in the calcium and combination-therapy groups than in the vitamin D group reached the combined end point of a serum alkaline phosphatase concentration of 350 U per liter or less and radiographic evidence of nearly complete healing of rickets (61 percent, 58 percent, and 19 percent, respectively; P<0.001).

CONCLUSIONS

Nigerian children with rickets have a low intake of calcium and have a better response to treatment with calcium alone or in combination with vitamin D than to treatment with vitamin D alone.

Vitamin A and immunity to viral, bacterial and protozoan infections

Studies in animal models and cell lines show that vitamin A and related retinoids play a major role in immunity, including expression of mucins and keratins, lymphopoiesis, apoptosis, cytokine expression, production of antibody, and the function of neutrophils, natural killer cells, monocytes or macrophages, T lymphocytes and B lymphocytes. Recent clinical trials suggest that vitamin A supplementation reduces morbidity and mortality in different infectious diseases, such as measles, diarrhoeal disease, measles-related pneumonia, human immunodeficiency virus infection and malaria. Immune responses vary considerably during different infections, and the available data suggest that the modulation of immune function by vitamin A may also vary widely, depending on the type of infection and immune responses involved.

Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety

For adults, the 5-microg (200 IU) vitamin D recommended dietary allowance may prevent osteomalacia in the absence of sunlight, but more is needed to help prevent osteoporosis and secondary hyperparathyroidism. Other benefits of vitamin D supplementation are implicated epidemiologically: prevention of some cancers, osteoarthritis progression, multiple sclerosis, and hypertension. Total-body sun exposure easily provides the equivalent of 250 microg (10000 IU) vitamin D/d, suggesting that this is a physiologic limit. Sailors in US submarines are deprived of environmentally acquired vitamin D equivalent to 20-50 microg (800-2000 IU)/d. The assembled data from many vitamin D supplementation studies reveal a curve for vitamin D dose versus serum 25-hydroxyvitamin D [25(OH)D] response that is surprisingly flat up to 250 microg (10000 IU) vitamin D/d. To ensure that serum 25(OH)D concentrations exceed 100 nmol/L, a total vitamin D supply of 100 microg (4000 IU)/d is required. Except in those with conditions causing hypersensitivity, there is no evidence of adverse effects with serum 25(OH)D concentrations <140 nmol/L, which require a total vitamin D supply of 250 microg (10000 IU)/d to attain. Published cases of vitamin D toxicity with hypercalcemia, for which the 25(OH)D concentration and vitamin D dose are known, all involve intake of > or = 1000 microg (40000 IU)/d. Because vitamin D is potentially toxic, intake of >25 microg (1000 IU)/d has been avoided even though the weight of evidence shows that the currently accepted, no observed adverse effect limit of 50 microg (2000 IU)/d is too low by at least 5-fold.

Nutritional rickets in suburbia

OBJECTIVE

Vitamin D deficiency continues to be a problem in pediatrics. This report presents four children, one Caucasian male and three African-American females aged 4 to 24 months who were treated for vitamin D deficiency rickets.

METHODS

One female was diagnosed in the Emergency Department during evaluation of a viral syndrome, another presented with hypocalcemic seizures and the third was a self-referral for evaluation of widened wrists. The male had biochemical rickets discovered incidentally during a hospitalization for pneumonia. All were breastfed without formula supplements. The 24-month female had severe cow and soy protein allergies and received multivitamin supplements intermittently. Birth order was from third to sixth child. Two families practiced Islam and the mothers wore veils. The females had a weight deficit for height. The females demonstrated a rachitic rosary, widening of the wrists and leg bowing. At diagnosis the serum calcium was 5.0-8.6 mg/dl, the inorganic phosphorus was 1.5-3.9 mg/dl and the alkaline phosphatase was 408-3324 U/L. The serum intact parathormone levels and the vitamin D levels were measured at Nichols Laboratories. The 25-OH vitamin D levels were 2-22 ng/ml and the 1,25(OH)2 vitamin D levels were 14-122 pg/ml. All had elevated parathormone levels. The three females had roentgenographic evidence of rickets. Two of the children also demonstrated iron deficiency.

RESULTS

All patients responded to Vitamin D supplements, beginning at 2000 IU for the male and 8,000-10,000 IU daily for the females. Two children were also given calcium supplements. The three females all showed complete healing of the rickets radiologically within six months. The serum intact parathormone demonstrated an inverse correlation with the serum calcium during recovery (r=-0.669; p<0.05).

CONCLUSION

Vitamin D deficiency does still occur. Breastfed children of multiparous mothers, with increased skin pigmentation, living in the higher latitudes are at increased risk and would benefit from vitamin D supplementation while breastfeeding.