Changes in bone mineral parameters, vitamin D metabolites, and PTH measurements with varying chronic kidney disease stages.

Vitamin D deficiency is associated with an increased risk of many diseases (skeletal and nonskeletal). Emerging data also associate high concentrations of serum parathyroid hormone (PTH) with morbidity and increased mortality in patients both with and without known chronic kidney disease (CKD). Understanding the relationship between vitamin D and PTH and the determinants of PTH is therefore important. We performed a cross-sectional study of 203 patients with varying stages of CKD randomly recruited from the Renal Unit database at our institution. Detailed case review was performed, and samples of fasting blood were taken for biochemical analyses. We measured standard biochemistry, 25-hydroxyvitamin D (25-OHD), 1,25-OHD, and three PTH measurements [1-84 PTH, total PTH, and derived N-terminal truncated, 7-84 PTH (cPTH)]. Vitamin D deficiency was high, with 86% of patients having 25-OHD levels below 30 ng/ml. Estimated glomerular filtration rate (eGFR) was not associated with 25-OHD levels, whereas 1,25-OHD was lower in those with CKD stage 5 versus stage 4, who were not treated with vitamin D metabolites (18 vs. 65 pg/ml, respectively; P < 0.05). All three PTH measurements increased with worsening eGFR, with this finding being more pronounced in those patients who were not treated with vitamin D metabolites. The slope of the regression line of cPTH on eGFR tended to be steeper, -0.90, compared to -0.81 for total PTH and -0.80 for 1-84 PTH (P = 0.06). The ratio of total PTH to cPTH did decrease significantly through the range of CKD stages (P = 0.03). The determinants of PTH were similar for all three PTH measurements, with eGFR having a strong inverse relationship, with weaker relationships for 25-OHD and ionized calcium on multivariate analyses. We confirm that there is a complex relationship between 25-OHD, eGFR, and PTH. Total PTH, 1-84 PTH, and cPTH increase with increasing CKD stages, with a relatively greater increase in cPTH, although the clinical significance of this finding remains uncertain. The three PTH measurements had similar correlations with the biochemical and clinical variables studied, suggesting that either total PTH or 1-84 PTH can be used in clinical practice when evaluating vitamin D and PTH status.

Differential diagnosis of chylothorax in a patient on parenteral nutrition: a case report.

Parenteral nutrition (PN) is widely used when enteral feeding is contraindicated or not possible in patients who are malnourished or at risk of malnutrition, but it is not without complications. We describe the rare complication of PN-related chylothorax that can lead to extensive investigations if not picked up early with clinical suspicion and simple biochemical tests.

Urinary and plasma organic acids and amino acids in chronic fatigue syndrome.

Previous work by others have suggested the occurrence of one or more chemical or metabolic 'markers' for ME/CFS including specific amino acids and organic acids and a number of unidentified compounds (CFSUM1, CFSUM2). We have shown elsewhere that CFSUM1 is partially derivatised pyroglutamic acid and CFSUM2 partially derivatised serine and have suggested and demonstrated that the analytical methods used were unsuitable to identify or to accurately quantify urinary metabolites. We have now made a detailed analysis of plasma and urinary amino acids and of urinary organic acids from patients with ME/CFS and from three control groups. Fasting blood plasma and timed urine samples were obtained from 31 patients with CFS, 31 age and sex-matched healthy controls, 15 patients with depression and 22 patients with rheumatoid arthritis. Plasma and urinary amino acids and urinary organic acids were determined using established and validated methods and data compared by statistical analysis. None of the previously reported abnormalities in urinary amino acids or of organic acids could be confirmed. Results however provide some evidence in patients with ME/CFS for underlying inflammatory disease and for reduced intramuscular collagen with a lowered threshold for muscle micro-injury. These factors in combination may provide a basis for the fatigue and muscle pain that are the major symptoms in these patients.

Anaphylactic reaction to intravenous sinistrin (Inutest).

Inulin clearance is the 'gold standard' for the determination of glomerular filtration rate. This is the first report of anaphylaxis following intravenous administration of inulin.