Does anyone have a paediatric protocol for a bicarbonate load test?
We are investigating a 4 year old who has an x-ray diagnosis of
osteopetrosis. The diagnosis which was made following a routine X-ray
of a fracture. The child is deaf but has none of the haematological
hallmarks of the lethal variant. Our routine investigations revealed a
suggestion of renal tubular acidosis which may indicate that this
patient is suffering from the milder form of osteopetrosis associated
with carbonic anhydrase deficiency:
Serum bicarbonate(venous) 21.6 mmol/L (22 - 30)
Venous pH 7.354
serum lactate 1.8 mmol/L (0.63 - 2.4)
Serum chloride 104 mmol/L (96 - 109)
Urine pH 7.17
Overnight culture of urine no significant growth
(This urine specimen was taken a week after the blood, unfortunately,
due to the difficulties encountered during phlebotomy
The text books suggest that a bicarbonate load test should help.
I understand the theory, but can anyone help with a protocol for the
bicarbonate load test which is practical in an uncooperative 4 year old?
I think that it is possible to measure red cell carbonic anhydrase
isoenzymes but nobody in the UK is listed as offering the service.
--
Robert Hill
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