Diagnosing Variable Primary Aldosteronism.

Study Overview
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Brief Summary
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The goal of this observational study is to see if there is a cyclical or exaggerated diurnal variation in aldosterone production in people with Primary Aldosteronism.

Detailed Description
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The main questions it aims to answer are: Can we diagnose more people if we used 24 hour urine measurements? In those with high amounts of aldosterone in their urine, is there a variable pattern to their aldosterone production? Participants will have a 24 hour urine measurement. They will also have multiple blood tests throughout the day to study the variability in aldosterone secretion.

Official Title
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Do we Miss a Common Subset of Primary Aldosteronism in Which There is Cyclical or Exaggerated Diurnal Variation in Secretion?

Conditions
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Primary Aldosteronism, High Blood Pressure

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: People with clinically suspected PA but have not met criteria for diagnosis. Suspicion based on low-renin (renin activity <0.5 nmol/h/L or renin mass <5 ng/L), plasma sodium > 140mmol/L or plasma potassium < 4mmol/L. Patients who have been diagnosed with PA and had previous aldosterone samples <277 pmol/L, a level which would normally not qualify for confirmatory testing. Patients with aldosterone results done at different times that indicate variability in production. Willing to consent and participate in the study. Exclusion Criteria: Inability to withdraw β-adrenoceptor antagonist therapy for 2 weeks. People on end of life treatment.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Sensitivity and specificity of 24 hour urine tetrahydroaldosterone excretion. | Can measurement of 24 hour urine tetrahydroaldosterone excretion detect more people with PA than current conventional screening tests? | 12 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Differences in timed day and night urine THA measurements. | We will be measuring the 24 hour urine THA samples in two separate (approximately 12 hours each) collections, one in the day and one at night. We can then study if there are any differences between day time and night time secretion which may help us understand the diurnal variation in aldosterone secretion. | 12 months | 
| Variation in aldosterone secretion from day series in those with positive 24h urine THA and those with negative 24h urine THA. | This will allow us to study further if the reason why their screening blood test did not meet the threshold for diagnosis. | 12 months | 
| Complete or partial clinical cure rate of this cohort of patients that qualify for adrenalectomy | Complete clinical cure is daytime home or ambulatory BP < 135/<85mmHg, on no treatment. Partial clinical cure is BP < 135/<85 mmHg on the same or fewer drugs, not including a K+-sparing diuretic. | 12 months | 
| Complete biochemical cure of PA in this cohort of patients that qualify for adrenalectomy. | This is defined as (whilst off medications that might alter serum potassium or the RAS) by both: normalization of serum potassium and normalization of ARR or elevated ARR and either baseline PAC <190pmol/L, or normal confirmatory test (saline infusion test or captopril challenge test). | 12 months |