We examined 748 stable MHD outpatients in southern California and followed them for up to 5 years (October 2001¨CDecember 2006).
In 748 MHD patients, serum PTH <150 pg/mL was more prevalent among non-blacks and diabetics. There was no association between serum PTH and coronary artery calcification score, bone mineral density, or dietary protein or calorie intake. Low serum PTH was associated with markers of protein-energy wasting and inflammation, and this association confounded the relationship between serum PTH and alkaline phosphatase. Although 5-year crude mortality rates were similar across PTH increments, after adjustment for the case-mix and surrogates of malnutrition and inflammation, a moderately low serum PTH in 100?50 pg/mL range was associated with the greatest survival compared to other serum PTH levels, i.e., a death hazard ratio of 0.52 (95 % confidence interval: 0.29?.92, p < 0.001) compared to PTH of 300?00 pg/mL (reference).
Low serum PTH may be another facet of the malnutrition-inflammation complex in CKD, and after controlling for this confounder, a moderately low PTH in 100?50 pg/mL range appears associated with the greatest survival. Limitations of observational studies should be considered.