Rickets is a common condition in childhood, caused by deficiency of calcium, phosphorous and/or vitamin D.1 Defective bone mineralisation leads to abnormalities of growth plate cartilage, predominantly in long bones,1 causing symptoms that can include bone pain, bowing of the lower limbs and an abnormal gait, fragile bones, delayed growth and dental problems.2 Hypophosphataemia is the underlying mechanism of all forms of rickets; it results in reduced apoptosis of hypertrophic cells of the growth plate, causing them to accumulate, and reduced mineralisation of primary spongiosa in the metaphysis (new bone).1,3
Rickets can be acquired (nutritional) or inherited. Nutritional rickets is the most common form and is caused, in most cases, by a dietary deficiency of vitamin D or, more rarely, calcium or phosphorus.4 Inherited rickets can be vitamin D dependent, where hyposphosphataemia occurs as a result of defective absorption of dietary phosphate and calcium, and resulting secondary hyperparathyroidism,5 or vitamin D independent (ie not caused by a defect of vitamin D intake, secretion or action), where phosphate deficiency is the primary defect.1,6
X-linked hypophosphataemia (XLH) is the most common cause of heritable rickets, with an incidence of 1 in 20,000 live births, and occurs due to inactivating mutations in PHEX.1 XLH is often misdiagnosed as nutritional rickets, with which it shares many symptoms and biochemical findings. Correct and timely diagnosis of XLH is important however, as early initiation of treatment can result in improved outcomes.7
This module contains a series of 10 multiple choice questions, designed to get you thinking about the differential diagnoses of nutritional rickets, followed by a short video telling the story of a real-life patient with XLH.
Nutritional rickets: when should you consider a differential diagnosis?, made available on https://sponsored.m3medical.com/kyowa-kirin/ and organized by M3 (EU) Limited, is accredited by the European Accreditation Council for Continuing Medical Education (EACCME) to provide the following CME activity for medical specialists.
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Through an agreement between the European Union of Medical Specialists (UEMS) and the American Medical Association (AMA), physicians may convert EACCME credits to an equivalent number of AMA PRA Category 1 CreditsTM. Information on the process to convert EACCME credit to AMA credit can be found at https://www.ama-assn.org/.
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