Does this patient have primary aldosteronism based on their aldosterone and plasma renin activity levels?

Does This Patient Have Primary Aldosteronism?

No, this patient does not have primary aldosteronism based on the laboratory results. The aldosterone-to-renin ratio (ARR) is 0.5, which is well below the diagnostic threshold, and the plasma aldosterone concentration is only 5.2 ng/dL, which is below the minimum required for a positive screening test 1, 2.

Analysis of the Screening Test Results

Aldosterone-to-Renin Ratio Calculation

• The patient's ARR is calculated as: 5.2 ng/dL (aldosterone) ÷ 10.5 ng/mL/hr (plasma renin activity) = 0.5 2
• This ratio is dramatically below the screening threshold of ≥25-30 that suggests primary aldosteronism 1, 2
• The lab report itself correctly notes that an ARR ≤25 is within normal limits 2

Aldosterone Concentration Requirements

• The plasma aldosterone concentration is 5.2 ng/dL, which is below the minimum threshold of 10-15 ng/dL required for a positive screening test 1, 2
• Even if the ARR were elevated, the aldosterone level must be at least 10 ng/dL to interpret the test as positive for primary aldosteronism 1, 2
• This patient fails both criteria: the ratio is too low AND the absolute aldosterone level is insufficient 2

Plasma Renin Activity Assessment

• The plasma renin activity is 10.5 ng/mL/hr, which is markedly elevated above the normal upright range of 0.5-4.0 ng/mL/hr 2
• In primary aldosteronism, renin should be suppressed (typically <1.0 ng/mL/hr) due to autonomous aldosterone production 1, 2
• This elevated renin activity indicates appropriate physiologic feedback, not autonomous aldosterone secretion 1

Clinical Context and Additional Findings

Electrolyte Status

• The patient's potassium is 3.9 mmol/L, which is normal 1
• While hypokalemia is present in only 50% of primary aldosteronism cases, the absence of hypokalemia combined with normal ARR makes the diagnosis extremely unlikely 1, 2

Renal Function Considerations

• The patient has significantly impaired renal function (eGFR 35 mL/min/1.73m², creatinine 1.98 mg/dL) with severe proteinuria (albumin/creatinine ratio >2611 ug/mg) 2
• The elevated renin may reflect appropriate activation of the renin-angiotensin-aldosterone system in response to chronic kidney disease 3
• The renal impairment appears related to diabetic nephropathy (elevated glucose 127 mg/dL, massive proteinuria) rather than aldosterone-mediated damage 1

Important Caveats

Medication Interference

• The lab results do not specify whether the patient was taking medications that could interfere with ARR testing 2
• Beta-blockers, diuretics, and mineralocorticoid receptor antagonists should ideally be discontinued before testing, though this information is not provided 2
• However, given how far below the diagnostic threshold this patient's results are, medication interference is unlikely to change the interpretation 2

When to Consider Retesting

• If this patient develops resistant hypertension (requiring ≥3 antihypertensive medications including a diuretic), repeat screening would be warranted 1, 2
• If spontaneous or diuretic-induced hypokalemia develops, rescreening should be considered 1, 4
• If an adrenal mass is discovered incidentally on imaging, ARR testing should be repeated 1, 2

Conclusion on Diagnosis

This patient definitively does not have primary aldosteronism. The combination of a very low ARR (0.5 versus required ≥25-30), insufficient aldosterone concentration (5.2 ng/dL versus required ≥10 ng/dL), and elevated rather than suppressed renin activity all exclude this diagnosis 1, 2. No confirmatory testing is needed, and the patient should not be referred to an endocrinologist for primary aldosteronism evaluation 2.