Abstract
Rickets has been recognized increasingly in preterm infants (PTI) inspite of prophylactic Vitamin D. An increased plasma alkaline phosphatase activity (PAP) may be of value in diagnosis (1) but adequate reference data are lacking. This paper reports serial determinations of PAP together with plasma calcium (Ca) and inorganic phosphorus (P) in a group of 30 consecutive PTI birthweight 1580g (±0.41), of gestational age 31 weeks (±2.54), using carefully standardized analytical techniques (2). The initial mean PAP was 857 u/l (range 180-2250) at a mean post-conceptual age of 34.4 wks (r 29-38). This contrasts with the upper limit in childhood of 825 u/l and adults 330 u/l. Subsequently 18 infants showed the characteristic increase, peak and decrease pattern in PAP previously described (2). Of this group 4 had radiological proven rickets and a mean peak PAP of 3068 u/l (±443) while the remainder (14) had a mean peak value of 1548 u/1 (±194). Serial Ca and P determinations showed no significant change. The PAP was of bony origin. The data indicate that the upper normal limit of PAP in the PTI is 5 x the corresponding adult value. PAP exceeding 7.5 x the adult reference limit may be compatible with radiological detectable rickets. Anti-rachitic prophylaxis in PTI may have to be reviewed.
Ref. (1) PAP in the LBW baby, Kovar I, Mayne P. Proc. Paed. Res. Soc. Arch Dis Child, in press. (2) PAP in preterm infants. Kovar I, Mayne P. Act. Paed. Scand., in press.
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Kovar, I., Mayne, P., Barltrop, D. et al. 1146 PLASMA ALKALINE PHOSPHATASE ACTIVITY, NEONATAL RICKETS. WHAT IS NORMAL?. Pediatr Res 15 (Suppl 4), 633 (1981). https://doi.org/10.1203/00006450-198104001-01172
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DOI: https://doi.org/10.1203/00006450-198104001-01172
