Hypocalcaemic seizure surveillance highlights UK public health policy failings

By Eleanor McDermid, Senior medwireNews Reporter

The occurrence of 91 confirmed or probable hypocalcaemic seizures in children with vitamin D deficiency over a 2-year period in the UK highlights a failure to promote appropriate supplementation.

For the study, Emre Basatemur and Alastair Sutcliffe, from the UCL Institute of Child Health in London, used the British Paediatric Surveillance Unit (BPSU) reporting system to capture all instances of hypocalcaemic seizure due to vitamin D deficiency between September 2011 and 2013.

They chose to monitor hypocalcaemic seizures because these are likely to come to the attention of paediatricians, rather than other specialists, and so be captured in the BPSU reporting system. They also suspected that other manifestations of vitamin D deficiency would be more common than recommended for the system.

Speaking to medwireNews, Wolfgang Högler, Consultant Paediatric Endocrinologist from Birmingham Children’s Hospital, UK, who was not involved in the research, stressed that vitamin D deficiency results in a range of other problems, including rickets, osteomalacia and hypocalcaemic cardiomyopathy. Hypocalcaemic seizures are “just the tip of the iceberg” in the UK, he said.

Högler added that identifying a child with vitamin D deficiency indicates that the whole family is at high risk and needs lifelong supplementation. “But getting that message out is far beyond paediatric endocrinology.”

In total, there were 81 confirmed and 10 probable cases of hypocalcaemic seizure due to vitamin D deficiency, giving an estimated incidence of 3.49 per million children age 0 to 15 years. Levels of 25-OH-vitamin D were below 25 nmol/L in 86% of children and 71% of their mothers, yet 80% of the children did not have other clinical features of vitamin D deficiency.

Most (95%) of the children were infants aged between 0 and 2 years, with the others being adolescents aged 11 to 15 years. The rapid growth seen in these age groups increases the need for calcium and therefore vitamin D, which facilitates absorption of calcium in the gut.

Two of the children were less than 1 week old, implying that they were born to mothers who were vitamin D deficient and/or had a very low calcium intake during pregnancy.

In his role as the Coordinator of the ESPE Bone and Growth Plate Working Group, Högler has surveyed compliance with vitamin D supplementation during the first year of life in Europe. With the exception of parts of southern Europe, where sunlight levels are relatively high year-round, he says that compliance is generally at least 70%, and complications of vitamin D deficiency are extremely rare.

But there is one exception: “England sticks out like a sore thumb, I’m afraid. Only 5% of all infants in the UK take [vitamin D] supplements.”

Although the UK Department of Health recommends vitamin D supplementation up to the age of 4 years, delivery of this advice is in the hands of general practitioners, midwives and health visitors, who Högler believes “are not getting the message across”.

“One of the main differences between England and other European countries is that [children’s] healthcare is in the hands of paediatricians,” he said. “And the most important difference is that there’s payment by result.” Paediatricians in the rest of Europe therefore have a financial incentive to ensure prescription of vitamin D supplements.

In addition to this, the UK has a relatively high proportion of South Asian and Afro-Caribbean immigrants, whose darker skin, diets that are traditionally low in calcium, and in some cases traditional dress put them at particular risk of vitamin D deficiency.

High-risk groups living in countries such as the UK require vitamin D supplementation for their whole lives. However, Högler believes that food fortification, as successfully implemented in a number of other countries, is “the most efficient way to eradicate osteomalacia and rickets.”

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