We compared plasma phosphate concentrations in general practice patients and hospital inpatients and outpatients over an 8-month period. The distribution of results in all three groups was similar and 12–16% of results were at or below 0·8 mmol/L. In general practice patients, 8·3% of results from males and 12·1% from females were below the lower limit of their respective reference ranges. Eighteen of these patients (0·2% of results) had plasma phosphate concentrations ⩽ 0·4 mmol/L. On follow-up, only two of these patients had any attributable cause for their severe hypophosphataemia; in the remainder, it was unexpected and unexplained. Hypophosphataemia in outpatients and general practice patients is more common than has previously been appreciated. We present a strategy for further investigation of these patients.

We have measured the urinary excretion of total protein, albumin and retinol binding protein (RBP) in random urine specimens obtained from 40 female patients with systemic lupus erythematosus (SLE). Thirty-three of these patients had no clinical evidence of any renal impairment (non-renal SLE); seven had overt renal disease (renal SLE). RBP: creatinine ratios were significantly higher in non-renal SLE patients compared with female controls ( P = 0·002). There was no significant difference between urine total protein concentrations, albumin: creatinine or total protein: creatinine ratios in non-renal SLE patients when compared with controls, despite approximately 20% of these patients having elevated excretion of total protein or albumin. All seven renal SLE patients had elevated albumin: creatinine ratios but only four of them had an increased RBP: creatinine ratio. Of 29 non-renal SLE patients who had urinary total protein concentrations below 0·2 g/L, (i.e. approximating to a negative protein dipstick), 14 had increases in either albumin : or RPB: creatinine ratios. Only two patients had increases in both. In the absence of clinical evidence of renal disease, increases in urinary albumin or RBP excretion could indicate subclinical nephropathy and measurements may have a role in the early diagnosis and subsequent monitoring of renal disease in SLE.

OBJECTIVE To compare acid-base balance, lactate concentration, and haemodynamic and O2 transport variables during haemofiltration with replacement fluid containing 44.5 mmol/l Na+ lactate or 40 mmol/l Na+ HCO3- and 3 mmol/l lactic acid. DESIGN A prospective, randomized trial. SETTING A multidisciplinary, adult intensive care unit in a university hospital. PATIENTS Forty acidotic patients who required haemofiltration, were dependent on mechanical ventilation, and had PA catheters in situ. INTERVENTIONS During haemofiltration patients received lactate or bicarbonate replacement fluid at a mean rate of 1.7 l/h (SD 0.3). Arterial blood gases, plasma lactate, and haemodynamic and O2 transport variables were measured before and after 12 and 24 h haemofiltration. Ultrafiltrate was collected for lactate estimation. MEASUREMENTS AND MAIN RESULTS As means (SD). The net gain of lactate was 63 mmol/h (12 mmol) with Na+ lactate and 0 mmol/h (0.3 mmol) with Na+ HCO3-. There was a significant increase in pH and [lactate] in both groups, but [lactate] was higher in patients receiving lactate. Twenty-one patients survived to ICU discharge, these patients were significantly less acidotic after filtration (lactate group: 0 h: pH 7.23 (0.09), [lactate] 2.4 mmol/l (1.7); 12 h: pH 7.34 (0.09), [lactate] 4.7 mmol/l (2.4); 24 h: pH 7.36 (0.07), [lactate] 4.7 mmol (2.7). HCO3 group: 0 h: pH 7.23 (0.09), [lactate] 2.3 (1.3); 12 h: pH 7.32 (0.06), [lactate] 2.9 mmol/l (1.8); 24 h: pH 7.35 (0.08), [lactate] 2.8 mmol/l (2.0). Base deficit: survivors: 0 h: 9 mmol/l (4); 12 h: 2 mmol/l (3). Non-survivors: 0 h: 10 mmol/l (3); 12 h: 6 mmol/l (3)). Haemodynamic and O2 transport variables were not significantly affected by treatment group or outcome. CONCLUSIONS The degree of correction of acidosis during the first 24 h of haemofiltration was determined by patients outcome but was not affected by the substitution of bicarbonate- for lactate-containing replacement fluids.

Urea and creatinine clearances achieved using continuous veno-venous haemofiltration were calculated in 16 critically ill patients, during 50 episodes of filtration. The effects of filter life and the volume of ultrafiltrate on these clearances were also evaluated. Clearances were calculated from urea and creatinine concentrations in blood and ultrafiltrate and the volume of ultrafiltrate produced. The overall mean (SD) urea clearance was 26.6 (6.0) ml.min-1 and the overall creatinine clearance was 30.1 (6.3) ml.min-1. The mean (SD) ultrafiltrate production was 29.6 (5.9) ml.min-1. Creatinine clearance was significantly lower in filters that failed within 24 h (filters < 24 h 27.5 (6.3) ml.min-1; filters > 24 h 32.2 (5.5) ml.min-1). The clearance of both solutes increased with increasing ultrafiltrate volume (p < 0.001). We conclude that satisfactory clearance of urea and creatinine can be achieved using continuous veno-venous haemofiltration. Increases in ultrafiltrate production lead to similar increases in urea and creatinine clearance. Prolongation of filter life may improve creatinine clearance.

Objective: To describe changes in lactate and acid-base balance during continuous venovenous haemofiltration with replacement fluid containing 44.5 mmol/l of sodium lactate. Design: Prospective observational study. Setting: Intensive Care Unit of a university teaching hospital. Subjects: Seventeen consecutive critically ill patients requiring haemofiltration with fluxes of 1,800 ml/hr. Interventions: Collection of blood samples and cardiac output measurement before haemofiltration and after 18 litres and 36 litres of replacement fluid. Collection of ultrafiltrate. Measurements and main results: During 17 episodes of filtration lactate was measured in plasma and ultrafiltrate. Arterial blood gases and oxygen saturation were measured and oxygen transport variables calculated. Seven patients survived and 10 died during filtration. Lactate increased significantly from 3.0±1 mmol/l before filtration to 6.0±2 after 18 litres replacement and 6.1±2 after 36 litres. Survivors showed significant increases in pH during filtration and significant differences from non-survivors after both 18 litres and 36 litres fluid replacement. (Survivors: pre-filtration-pH 7.24±0.09, post-18 litres-pH 7.40±0.08, post-36 litres-pH 7.42±0.04. Non-survivors: pre-pH-7.23±0.09, post-18 litres-pH 7.20±0.13, post-36 litres-pH 7.30±0.08.) Corresponding oxygen transport variables did not show significant differences between groups. Conclusion: Lactate increases during filtration but acid-base abnormalities are corrected in survivors. Persistent acidosis after 18 litres replacement is associated with a poor prognosis.

The stability of retinol binding protein (RBP) in urine has been reassessed and was found to be pH-dependent, diminishing as urinary pH decreased. When urines were incubated at 4 degrees C for 1 week, statistically significant losses of RBP were observed at pH values less than seven, varying in degree in different urines. At 37 degrees C some urine specimens showed minor losses when incubated for periods up to 4 h. This was more marked at pH 5 than pH 7 with maximum losses of 26% and 12%, respectively. When adjusted to pH 7, urines showed no significant loss of RBP when stored at 4 degrees C for up to 2 weeks; at -20 degrees C no significant change in RBP concentration was found for at least 14 weeks. To minimize losses of RBP it is recommended that urine pH is adjusted to above seven immediately after voiding.

Sequential timed samples were taken from patients after a single dose of a new cephalosporin--Cefpirome HR810. The patients had been recruited in a multi-centre trial over a 12-month period. Creatinine was estimated in all of these specimens by four different techniques, embodying four different analytical principles. Interference from the drug was evident in the assay depending on the Jaffe reaction. There was also interference in the enzyme-based methods, manifested as increased imprecision due to a non-specified cause thought to be related to the age of the samples. Only the HPLC method guaranteed precise results free from drug interference.

Journal Article Bilirubin interference in determinations of creatinine with the Hitachi 737 analyzer Get access J M Guy, J M Guy Clin. Chem. Dept., East Birmingham Hosp., U.K Search for other works by this author on: Oxford Academic Google Scholar E F Legg E F Legg Clin. Chem. Dept., East Birmingham Hosp., U.K Search for other works by this author on: Oxford Academic Google Scholar Clinical Chemistry, Volume 36, Issue 10, 1 October 1990, Pages 1851–1852, https://doi.org/10.1093/clinchem/36.10.1851 Published: 01 October 1990

An improved HPLC method for the measurement of serum creatinine is described. Separation is effected using a strong cation exchange column at pH 4.7. Analytical recovery, precision and linearity are satisfactory, and the method correlates well with a kinetic Jaffé procedure. The method provides a means of accurately measuring creatinine and may be of use in the investigation of interference in creatinine assays.

An enzyme electrode for urine oxalate measurement has been produced using acrylamide gel-entrapped oxalate decar☐ylase retained over a CO2 sensor. Urine required pre-treatment with EDTA, but oxalate extraction was not necessary and inhibition by phosphate and sulphate was not apparent until after 10–14 days. The linear range was 0–0.2 mmol/l. Analysis of 50 urine specimens diluted 1 in 10 in pH 3.0 glycine buffer showed good correlation with a widely-used colorimetric method (y = 1.101x − 0.018, r = 0.955).