The girl, now 24-month old, is the only child of the family. She was soon
diagnosed to have craniostenosis after birth. The clinicians concentrated
on the skull & airway problems all along. Low serum phosphate level
(typically 0.3-0.7 mmol/L) was noticed later. Retrospectively, the
phosphate level was reviewed and it was normal at first 6 months of life.
Alkaline phosphatase (ALP) was normal (or low for her age, about 150 - 200
U/L). Serum calcium and PTH levels were normal. TmPO4: 63% (low), urine
calcium excretion was normal. We do not have facility to measure vitamin D
or its metabolites. Skeletal survey showed severe osteopenia with multiple
greenstick fracture. The patient was treated by frequent oral phosphate
solution and calcitriol.
Question: Is this a case of X-linked hypophosphataemia (XLH) with unusually
normal ALP? Has anyone seen a case of XLH with normal ALP? Any other
thoughts? Possibility of Fanconi syndrome is being investigated. All
comments are welcome.
Tony Mak
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Dr Tony Mak, MRCPath, FRCPA
Department of Clinical Pathology
Tuen Mun Hospital
Tuen Mun
Hong Kong
CHINA
Email: [log in to unmask]
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