Macroprolactin on the Advia Centaur: experience with 409 patients over a three-year period.

INTRODUCTION: Macroprolactin (MPRL) is an important source of interference that may lead to misdiagnosis and mismanagement of hyperprolactinaemic patients. Prolactin assays exhibit considerable variation in the detection of MPRL. In this study, we examine the requirement for polyethylene glycol (PEG) precipitation in the analysis of hyperprolactinaemia detected by the Advia Centaur as it has a relatively low reactivity with MPRL. METHODS: Four hundreds and sixty-four hyperprolactinaemic samples were collected from the laboratory information system for Saint James University Hospital over a three-year period. These samples were screened for MPRL using PEG precipitation protocol. Monomeric prolactin concentration post-PEG precipitation was compared with a reference range determined by PEG precipitation in normal subjects. RESULTS: MPRL was the cause of hyperprolactinaemia in 4% of patients (16/409) over the three-year period studied. Nine subjects with MPRL also had elevated monomeric prolactin. CONCLUSIONS: PEG screening is still needed for assays with low MPRL reactivity such as the Advia Centaur and this should be performed with a locally derived reference range for monomeric prolactin.

Acute liver failure in pregnancy associated with maternal MCAD deficiency.

In recent years the association between severe pregnancy complications and fetal fatty acid oxidation (FAO) disorders has been reported. However, there are few descriptions of a maternal FAO disorder leading to these complications. We describe acute liver failure associated with an undiagnosed maternal medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. The previously healthy proband presented at the 39th week with an itchy rash, palmar erythema and trace proteinuria; she was admitted onto a maternity ward. Acute fatty liver was suspected from the blood tests and a Caesarean section was performed, delivering a healthy boy. Cord blood samples were taken at delivery as part of an ongoing research project. The analysis of the cord blood sample showed a high concentration of octanoylcarnitine of 2.3 micromol/L (reference <0.1), suggesting a possible fatty acid oxidation disorder. However, subsequent acylcarnitine analyses of the baby's blood showed a normal pattern. The proband was further evaluated by urine organic acids and acylcarnitine profile. Elevated concentrations of hexanoylglycine in urine and octanoylcarnitine in blood spots were found, consistent with a diagnosis of MCAD deficiency. Mutation analyses confirmed that she was homozygous for c.985A>G (K329E). Even though these pregnancy complications are rare and it is not possible to affirm that the proband's acute liver failure was secondary to an undiagnosed MCAD deficiency, it seems likely.