This is an observational study compares the positivity rates of two tests for screening for primary aldosteronism: plasma aldosterone renin ratio and 24-hour urine aldosterone in patients with young-onset hypertension with or without other clinical features of primary aldosteronism.

Plasma aldosterone and renin measurements are subject to significant intra-individual variability, including variation related to posture, time of day and sodium balance. Aldosterone secretion is not constant and may be subject to diurnal variation. As such one-off testing of ARR, does not consider the salt status of the individual necessitating repetition of tests to ensure false negative or false positive test results are ruled out. The value of accumulated aldosterone in a 24-hour sample has the advantage that it does not depend on circadian variation. This pilot observational study will help establish the positivity rates of both standard plasma aldosterone renin ratio and 24-hour urine aldosterone, and the degree to which they correlate but will help establish if untargeted screening in young-onset hypertension is feasible and test the robustness of current standard guidelines for primary aldosteronism screening and case confirmation.

Inclusion Criteria:

• A patient will be eligible for inclusion in this trial only if all of the following criteria apply:

  • Aged 18 years and above.
  • Meets NICE criteria for a diagnosis of hypertension with an age of onset of hypertension between 18-60 years.
  • For cohort 2 (suspected primary aldosteronism): resistant hypertension, and/or hypertension with spontaneous or diuretic-induced hypokalaemia, and/or hypertension.

Exclusion Criteria:

• • Severe hypertension (sustained blood pressure of >200/110 mmHg) or a history of known secondary hypertension other than PA.

  • Contraindications to confirmatory testing with saline infusion or oral salt loading test as per standard clinical criteria such as known clinical diagnosis of heart failure, and/or chronic kidney disease stage 3b.
  • Known Pregnancy or breast feeding.
  • Lack of informed consent.
  • Any medical condition deemed unsuitable by investigator for participation in the study

To enable the inclusion of a diverse population, representative of the UK in terms of ethnicity, and geographical and environmental factors that affect blood pressure and PA, we aim to conduct the study at several specialist hypertension sites in the UK. We will recruit patients referred to one of the study sites with hypertension (NICE definition) who fall into one of the following groups (cohorts):

Cohort 1: Adult patients (18-75 years of age) with onset hypertension (≤60 years of age) but without other obvious features of PA Cohort 2: Adult patients (18-75 years of age) with onset hypertension (≤60 years of age) with one of the features: low serum potassium, or resistant hypertension.