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Rickets is a condition in which there is failure of normal mineralisation (osteomalacia) of growing bone. Whilst osteomalacia may be present in adults, rickets cannot occur. It is generally caused by a lack of mineral supply which can either be as a result of deficiency of calcium (calciopaenic rickets) or of phosphate (phosphopaenic rickets) although, in addition, renal tubular acidosis may also interfere with the process of mineralisation and cause rickets. Only calciopaenic and distal renal tubular disorders will be discussed in this chapter. The commonest cause of rickets is still vitamin D deficiency which is also responsible for problems other than rickets. Disorders of vitamin D metabolism or responsiveness may also cause similar problems. Distal renal tubular acidosis may be caused by a variety of metabolic errors similar to those of osteoclasts. One form of DRTA also causes a form of osteopetrosis. This chapter describes these conditions in detail and sets out a logical approach to treatment., (Copyright (c) 2009 S. Karger AG, Basel.)

Hypophosphataemic rickets (HR) is usually secondary to renal phosphate wasting but may occur secondary to reduced intake or absorption of phosphate. We describe a series of cases of HR associated with the use of Neocate®, an amino-acid based formula (AAF). A retrospective review of cases with HR associated with AAF use presenting to centres across the United Kingdom. 10 cases were identified, over a 9 month period, all associated with Neocate® use. The age at presentation was 5 months to 3 years. The majority (8/10) were born prematurely. Gastro oesophageal reflux disease (6/10) was the most frequent indication for AAF use. Radiologically apparent rickets was observed after a median of 8 months (range 3–15 months) of exclusive Neocate® feed. The majority (7/10) were diagnosed on the basis of incidental findings on radiographs: rickets (6/10) or fracture with osteopenia (5/10). All patients had typical biochemical features of HR with low serum phosphate, high alkaline phosphatase, normal serum calcium and 25 hydroxyvitamin D. However, in all cases the tubular reabsorption of phosphate (TRP) was ≥96%. Phosphate supplementation resulted in normalisation of serum phosphate within 1–16 weeks, and levels remained normal only after Neocate® cessation. In patients with sufficient follow up duration (4/10), normalisation of phosphate and radiological healing of rickets was noted after 6 months (range: 6–8 months) following discontinuation of Neocate®. The presence of a normal TRP and resolution of hypophosphataemia and rickets following discontinuation of Neocate® indicates this is a reversible cause likely mediated by poor phosphate absorption. Close biochemical surveillance is recommended for children on Neocate®, especially in those with gastrointestinal co-morbidities, with consideration of a change in feed or phosphate supplementation in affected children. [ABSTRACT FROM AUTHOR]

Aims: To describe the various ways in which vitamin D deficiency presents in children in selected districts of London and to identify which factors, if any, determine the mode of presentation. Methods: Retrospective review of patients presenting to Newham General, Royal London, Great Ormond Street, and King's College Hospitals between 1996 and 2001 with either hypocalcaemia or rickets caused by vitamin D deficiency. Children with plasma 25-hydroxyvitamin D levels <25 nmol/l (10 ng/ml) were considered to have vitamin D deficiency. Results: Sixty five children, mostly from Black or Asian ethnic minority groups, were identified, 29 of whom had hypocalcaemic symptoms. Seventeen of these had no radiological evidence of rickets. The remainder (48 children) had radiological evidence of rickets with or without clinical signs. Symptoms and signs reverted to normal in all cases with vitamin D supplementation. All children who presented with symptomatic hypocalcaemia were aged either <3 or >10 years. There was a strong correlation between age at presentation and population growth velocity reference data. Conclusions: Rickets remains a problem in the UK especially in "at risk" ethnic minority groups. Symptomatic hypocalcaemia is an important, but under-recognised presenting feature. Growth rate is likely to be an important factor in determining the mode of presentation. Unexplained hypocalcaemia should be attributed to vitamin D deficiency in "at risk" ethnic minority groups until proved otherwise. [ABSTRACT FROM AUTHOR]

The article presents information on nutritional rickets. Rickets is a relatively rare condition in western societies and when it presents, is often associated with some form of metabolic disturbance of vitamin D metabolism, which may be primary or secondary or a defect in renal tubular function. However, over the past few years several reports have appeared which have suggested that nutritional rickets is reappearing in Great Britain and North America in a variety of ethnic groups. Some reports have suggested that rickets that occurs in Great Britain is seen in patients of black or Asian origin and it is well recognized that the darker skin color of these ethnic groups is a contributing factor to the high incidence of nutritional vitamin D deficiency.