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We developed and evaluated a method for the separation of delta bilirubin (B delta) by micro-column affinity chromatography based on Cibacron Blue 3G-A-Agarose. Untreated serum was applied to affinity columns and free non-protein bound bilirubins were eluted with phosphate buffer containing 20 g/l Triton X-100. Retained albumin was eluted using caffeine-benzoate reagent and bilirubin associated with this fraction (B delta) quantitated by the method of Jendrassik and Gróf modified by Doumas et al (Clin Chem 1985;31:1779-1789); results correlated well with the high performance liquid chromatography (HPLC) method (n = 35, y (affinity) = 1.009x (HPLC)-5.49; r = 0.959) described by Lauff et al. (J Chromatography 1981;226:391-402). Two controls analyzed with each batch gave between-batch imprecision less than 4.0% (n = 10; Control 1, mean = 20.05 mumol/l; Control 2, mean = 74.82 mumol/l). Within-batch imprecision was less than 3.3% for both levels. Specimens collected from 25 neonates less than 20 days of age showed a B delta concentration of 1.7 +/- 0.7 mumol/l (mean +/- 1 S.D.) and percent B delta of 2.2 +/- 1.9 (mean total bilirubin +/- 1 S.D. = 118 +/- 79 mumol/l). Although time consuming, this simple and precise method allows the measurement of B delta in laboratories without the need for specialized instruments.

Elevated urinary albumin excretion is a marker for increased mortality and morbidity in European subjects with non-insulin-dependent diabetes. Urinary albumin excretion was compared in 32 Maoris, 34 Pacific Island Polynesians and 66 subjects of European origin with non-insulin-dependent diabetes attending a diabetes clinic in Wellington, New Zealand. The random urinary albumin to creatinine ratio was used as an estimation of urinary albumin excretion rate. The random urinary albumin to creatinine ratio was significantly higher in Maori and Pacific Island Polynesian subjects, compared to diabetic Europeans (geometric mean urinary albumin to creatinine ratios were 13.13, 12.00 and 2.79 mg/mmol respectively, P less than 0.05). These findings would be consistent with the high mortality and morbidity seen in the Maori and Pacific Island Polynesian diabetic populations. The correlation between hypertension and increased urinary albumin excretion was stronger in the Europeans than in the Maoris and Pacific Island Polynesians studied, suggesting that differences in blood pressure alone are unlikely to account for the observed differences in albumin excretion. Follow-up studies are required to determine whether diabetic Maoris and Pacific Island Polynesians with increased urinary albumin excretion have a similar prognosis to their European counterparts.