Association of serum parathyrine and calcium levels with primary aldosteronism: a meta-analysis.

Primary aldosteronism (PA) represents major cause of secondary hypertension, strongly associated with high cardiovascular morbidity and mortality. Aldosterone excess may influence mineral homeostasis, through higher urinary calcium (Ca) excretion reducing calcium plasma levels and leading to secondary increase of parathyrine (PTH). The purpose of the present study is to clarify the association of serum PTH and Ca levels with PA using a metaanalysis approach. We searched articles indexed in the PubMed, OVID and Sciencedirect published as of September 2014 that met our predefined criteria. Six articles with 748 subjects from 8 case-control studies were identified. Overall, pooled analysis indicated that subjects with PA had higher serum PTH concentrations and lower Ca levels than controls with essential hypertension (EH) (PTH: SMD = 1.146, 95% CI = [0.774, 1.518]; Ca: SMD = -0.698, 95% CI = [-1.102,-0.294]). Further subgroup analysis stratified by geological location found a similar pattern both in Italy and Austria (Italy: for PTH, SMD = 1.176, 95% CI = [0.758, 1.593], for Ca, SMD = -0.669, 95% CI = [-1.119,-0.219]; Austria: for PTH, SMD = 1.004, 95% CI = [0.359, 1.648], for Ca, SMD = -0.900, 95% CI = [-1.543,-0.257]). In addition, the subgroup analysis stratified by type of Ca measurement also found a similar pattern by spectrophotometry (SMD = -1.078, 95% CI = [-1.532, -0.623]), but not by ion selective electrode (SMD = -0.248, 95% CI = [-0.810, 0.315]). Sensitivity analysis showed that excluding any one study from the pooled analysis did not vary the results substantially. No evidence of publication bias was observed. In conclusion, this meta-analysis supports a significant association of PTH and Ca concentration with PA. Therefore, the high levels of PTH and low Ca concentrations in serum can be used as a variable predictor for PA.