Hypophosphatasia mimicking hypoxic–ischaemic encephalopathy: early recognition and management

Abstract

BackgroundHypophosphatasia (HPP) is a rare inherited disorder affecting bone and teeth development. Perinatal HPP is the most severe form and associated with a high mortality. Features include respiratory distress, skeletal abnormalities and low alkaline phosphatase (ALP) activity.CaseA baby boy developed respiratory distress, hypotonia and seizures within an hour of birth. Blood gas showed mixed acidosis and abnormal base deficit. Hypoxic–ischaemic encephalopathy (HIE) was suspected and managed with therapeutic hypothermia. Subsequent investigations identified low ALP activity and abnormal bone mineralisation, leading to a diagnosis of HPP. On day 5 of life, enzyme replacement therapy (ERT) was commenced, its first use via direct NHS England funding since UK licensing in 2017.ConclusionsEarly hypotonia is an atypical presentation for perinatal HPP. Combined with acidosis and encephalopathy, it can clinically mimic HIE. Early recognition of biochemical and radiological features of HPP is essential for rapid diagnosis and timely initiation of life-saving ERT.

Neonatal Bone Disorders

“…It is apparent at birth with short deformed limbs, severely hypomineralized skeleton, small chest with hypoplastic lungs and, in some cases, pyridoxine deficiency seizures. Perinatal HPP can mimic hypoxic ischemic encephalopathy (27) and delay diagnosis in the absence of antenatal suspicion. Low serum ALP level in the presence of typical radiological features of tongue-like lucencies in the metaphysis, rickets-like changes, and hypomineralized skeleton (Figures 1-3a-c) should clinch the diagnosis of HPP (28).…”

Metabolic bone diseases in full-term newborns: A review of the literature with case reports

“…Perinatal HPP, hipoksik iskemik ensefalopatiyi taklit edebilir. 69 Hipofosfatazya, genç yaşlarda raşitizm ve yaşamın daha sonraki dönemlerinde osteomalazi şeklinde ortaya çıkabilir. Nadiren neonatal dönemde ortaya çıkabileceği ve perinatal veya infantil HPP formlarıyla karıştırılabileceği için D vitamini eksikliğine bağlı raşitizminden ayırt edilmesi önemlidir.…”