Aim To examine transaminitis in obese children, its association with glucose metabolism and the metabolic syndrome and the response to weight loss through lifestyle modification.

Methods 216 children (90 male), aged 2.9–17.6 (median 12.4 years) with median body mass index (BMI) SD score (SDS) of 3.36 (range 1.92–6.22) attending a hospital obesity clinic in Bristol (UK) underwent an oral glucose tolerance test (OGTT) with fasting lipid and liver profile. Auxological measures included weight, height, waist circumference, percentage body fat. Parental history of type 2 diabetes (T2DM) was recorded. The 2007 International Diabetes Federation definition of metabolic syndrome was used. 90 children undergoing a trial of lifestyle modification to improve weight were re-assessed at 12 months.

Results 34/216 (16%) children had raised alanine aminotransferase (ALT) (>40 IU/l) with greater prevalence in boys (23% vs 10%, p=0.01) and in those with a parental history of T2DM (30% vs 13.2% p=0.019). Patients with transaminitis were more likely to fulfil the criteria for metabolic syndrome (p<0.001) and have subtle abnormalities in glucose metabolism during an OGTT with elevated glucose levels at 90 (p=0.041) and 120 (p=0.014) min and a greater glucose area-under-the-curve (p=0.014). Improvement in BMI SDS over 1 year correlated with improvement in ALT levels (τ = −0.29, p<0.001).

Conclusion Prevalence of transaminitis is significant in obese children and is associated with components of the metabolic syndrome. Lifestyle-based improvement in BMI SDS offers an effective tool for correcting transaminitis and should remain the central component of therapy.