Screening of primary aldosteronism by clinical features and daily laboratory tests: combination of urine pH, sex, and serum K

J Hypertens. 2018 Feb;36(2):326-334. doi: 10.1097/HJH.0000000000001511.

Abstract

Objective: To develop and validate a scoring system for selection of patients who should proceed to endocrinologic examinations of primary aldosteronism in newly diagnosed hypertensive patients.

Methods: A multivariate logistic regression analysis for primary aldosteronism was undertaken by use of seven possible primary aldosteronism markers, age less than 40 years, female sex, moderate-to-severe hypertension, hypokalemia, serum Na minus Cl at least 40 mmol/l, serum uric acid 237.92 μmol/l or less (4.0 mg/dl), and urine pH (U-pH) at least 7.0, in consecutive outpatients newly diagnosed with hypertension. The diagnostic criteria of primary aldosteronism were plasma aldosterone concentration-to-plasma renin activity ratio [ARR, (ng/dl)/(ng/ml per h)] at least 20 and at least one positive result in four types of challenge tests.

Results: Of 130 patients, 24 were diagnosed with primary aldosteronism. The area under the receiver operating characteristic curve (AUC) for a logistic model incorporating all possible primary aldosteronism markers was 0.73 [95% confidence interval (CI): 0.61-0.85]. Removing high U-pH, female sex, and hypokalemia from the full model decreased the AUC by 0.059, 0.035, and 0.011, respectively. We devised pH of urine, female sex, low serum K (PFK) score, in which one point each was assigned to high U-pH, female sex, and hypokalemia. The prevalences of primary aldosteronism in patients with 0, 1, 2, and 3 points were 11, 14, 42, and 60%, respectively. In external validation datasets (n = 106), AUC of PFK score was significantly higher than that of hypokalemia alone (0.73, 95% CI: 0.63-0.83 vs. 0.53, 95% CI: 0.44-0.63, P < 0.01).

Conclusion: PFK score may be a better parameter than hypokalemia alone for identifying patients with a high probability of having primary aldosteronism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aldosterone / blood
  • Area Under Curve
  • Biomarkers / blood
  • Biomarkers / urine
  • Female
  • Humans
  • Hydrogen-Ion Concentration
  • Hyperaldosteronism / blood
  • Hyperaldosteronism / complications
  • Hyperaldosteronism / diagnosis*
  • Hyperaldosteronism / urine
  • Hypertension / etiology*
  • Hypokalemia / blood
  • Male
  • Mass Screening
  • Middle Aged
  • Potassium / blood*
  • ROC Curve
  • Renin / blood
  • Sex Factors
  • Urinalysis

Substances

  • Biomarkers
  • Aldosterone
  • Renin
  • Potassium