Aldosterone Lab Results: Normal Reference Range vs. Functional Optimal

What Aldosterone Does and Why the Number on Your Lab Report Matters

Aldosterone is the body's primary mineralocorticoid, produced in the zona glomerulosa of the adrenal cortex. It acts on the kidneys to retain sodium and excrete potassium, directly regulating blood pressure and fluid balance. Too much drives hypertension, hypokalemia, and cardiovascular damage. Too little causes salt wasting, low blood pressure, and dangerous hyperkalemia.

The renin-angiotensin-aldosterone system (RAAS) governs aldosterone secretion in a feedback loop triggered by blood volume, sodium delivery to the distal nephron, and potassium concentration 1. When you receive a lab result showing your aldosterone level, that single number captures one snapshot of a dynamic hormonal axis. Posture, sodium intake, time of day, and medications all shift the value. A result of 4 ng/dL might be perfectly physiologic in someone lying supine on a high-sodium diet, or it might signal adrenal insufficiency in someone standing upright and sodium-depleted. Context is everything. The number alone is not a diagnosis.

Standard Reference Ranges: What "Normal" Actually Means

Most commercial laboratories report an upright (ambulatory) aldosterone reference range between 1 and 16 ng/dL, with supine ranges spanning roughly 3 to 16 ng/dL. Quest Diagnostics uses an upright range of 3.0 to 23.6 ng/dL, while Mayo Clinic Medical Laboratories cites an upright range of 3 to 24 ng/dL 2. These ranges vary because each laboratory derives its own 95th-percentile interval from its assay platform and reference population.

The 2016 Endocrine Society Clinical Practice Guideline on the Management of Primary Aldosteronism emphasizes that the absolute aldosterone value must always be interpreted alongside plasma renin activity (PRA) or direct renin concentration (DRC) 2. Dr. John W. Funder, lead author of the guideline, wrote: "An aldosterone-to-renin ratio is the most reliable screening test for primary aldosteronism, but the ratio must be interpreted in the context of the absolute aldosterone concentration" 2. A ratio above 30 (ng/dL per ng/mL/hr) with an aldosterone concentration above 15 ng/dL warrants confirmatory testing.

The word "normal" on a lab report means your result falls within two standard deviations of the lab's reference population. It does not mean the result is optimal for your cardiovascular health, electrolyte balance, or symptom profile. A patient with an aldosterone of 2 ng/dL is technically "normal" by many lab ranges, yet may experience orthostatic hypotension, fatigue, and salt cravings consistent with functional hypoaldosteronism.

Functional Optimal Ranges: A Different Clinical Lens

Functional and integrative practitioners often apply a narrower target window to aldosterone. The working range most commonly cited in functional endocrinology is 6 to 12 ng/dL for an upright morning sample. This range does not appear in any Endocrine Society guideline. It originates from clinical pattern recognition: patients whose aldosterone sits in this band, paired with a balanced sodium-potassium ratio and stable blood pressure, tend to report fewer symptoms of dysautonomia, fatigue, and fluid retention.

The distinction matters most at the margins. A patient with an aldosterone of 2.5 ng/dL and a renin of 0.5 ng/mL/hr has a low-normal ARR and a "normal" aldosterone by most lab standards. A functional clinician would flag the absolute aldosterone as suboptimal and investigate adrenal reserve, chronic stress burden, and sodium status. On the high end, a patient at 22 ng/dL with suppressed renin might pass a standard lab range cutoff but would screen positive for primary aldosteronism under the Endocrine Society criteria 2.

Neither framework is wrong. Standard ranges exist to catch pathology. Functional ranges exist to optimize physiology before pathology develops. The clinical question determines which lens to use.

The Aldosterone-to-Renin Ratio: The Real Screening Tool

The ARR is the single most important calculated value when evaluating aldosterone. The Endocrine Society guideline recommends screening with the ARR in all patients with sustained blood pressure above 150/100 mmHg, resistant hypertension (uncontrolled on three drugs), hypertension with spontaneous or diuretic-induced hypokalemia, hypertension with an adrenal incidentaloma, or a family history of early-onset hypertension or stroke before age 40 2.

A positive screen is defined as an ARR above 30 (when aldosterone is measured in ng/dL and PRA in ng/mL/hr) combined with an aldosterone above 15 ng/dL 3. The PASO (Primary Aldosteronism Surgical Outcome) study, which followed 705 patients across 31 centers, found that unilateral adrenalectomy produced complete clinical cure (normotension off all medications) in 37% of patients and significant improvement in another 47% 4.

The ARR is sensitive but not specific. False positives occur with beta-blocker use (which suppresses renin more than aldosterone), renal impairment, and advanced age. False negatives occur with ACE inhibitor or ARB use, diuretics, and dihydropyridine calcium channel blockers. The guideline recommends withdrawing mineralocorticoid receptor antagonists for at least four weeks and other interfering medications for at least two weeks before testing when clinically safe 2.

High Aldosterone: Primary Aldosteronism and Cardiovascular Risk

Primary aldosteronism (PA) affects between 5% and 10% of all patients with hypertension and up to 20% of those with resistant hypertension 5. A cross-sectional analysis published in the Annals of Internal Medicine found that PA patients had a significantly higher rate of atrial fibrillation (7.3% vs. 0.6%), myocardial infarction (4.0% vs. 0.6%), and heart failure (4.0% vs. 1.1%) compared to age- and sex-matched hypertensive controls with similar blood pressure levels 6.

This excess cardiovascular damage occurs independently of blood pressure. Aldosterone directly promotes myocardial fibrosis, endothelial dysfunction, and renal injury through mineralocorticoid receptor activation in tissues outside the kidney 7. The two main subtypes are aldosterone-producing adenoma (APA), which accounts for roughly 35 to 40% of cases and is treated surgically, and bilateral adrenal hyperplasia (BAH), which accounts for 60 to 65% and is managed with mineralocorticoid receptor antagonists like spironolactone (typically starting at 25 to 50 mg daily) or eplerenone (50 mg twice daily) 2.

Secondary hyperaldosteronism, where both aldosterone and renin are elevated, occurs in renovascular hypertension, congestive heart failure, cirrhosis, and nephrotic syndrome. The high renin distinguishes it from PA.

Low Aldosterone: Hypoaldosteronism and Its Consequences

Low aldosterone production, or hypoaldosteronism, is less commonly discussed but clinically significant. The most frequent form is hyporeninemic hypoaldosteronism (type 4 renal tubular acidosis), seen in diabetic nephropathy, mild-to-moderate chronic kidney disease, and NSAID use 8. Patients present with persistent hyperkalemia out of proportion to their glomerular filtration rate, mild non-anion-gap metabolic acidosis, and relatively preserved sodium balance.

Primary adrenal insufficiency (Addison's disease) causes deficiency of both cortisol and aldosterone. The European Society of Endocrinology guideline estimates a prevalence of 100 to 140 per million in European populations 9. Symptoms include orthostatic hypotension, salt cravings, hyperkalemia, and hyponatremia. Fludrocortisone at 0.05 to 0.2 mg daily is the standard mineralocorticoid replacement, titrated to normalize potassium and upright blood pressure 9.

The AACE/ACE 2017 guidelines on adrenal insufficiency state: "Mineralocorticoid replacement should be monitored by serum sodium, potassium, and plasma renin activity, with the goal of maintaining renin in the upper normal range" 10. This target maps closely to the functional concept of optimizing aldosterone effect rather than simply keeping labs inside a reference range.

How to Lower Aldosterone

Reducing aldosterone depends on the underlying cause. For primary aldosteronism caused by an APA, laparoscopic adrenalectomy is the preferred treatment, with the PASO study reporting complete biochemical cure in 94% of surgical patients 4. For BAH or patients who decline surgery, pharmacologic blockade is first-line.

Spironolactone at 25 to 100 mg daily remains the most studied mineralocorticoid receptor antagonist for PA. The PATHWAY-2 trial (N=335) demonstrated that spironolactone was superior to doxazosin and bisoprolol as add-on therapy for resistant hypertension, reducing home systolic blood pressure by an additional 8.7 mmHg compared to placebo 11. Eplerenone offers a more selective alternative with fewer anti-androgenic side effects, though it requires twice-daily dosing and is roughly half as potent milligram for milligram.

Dietary sodium restriction (below 2 to 000 mg daily) reduces aldosterone secretion by decreasing RAAS activation. Potassium supplementation (aiming for serum potassium of 4.0 to 4.5 mEq/L) also helps blunt aldosterone's downstream effects. Regular aerobic exercise at moderate intensity (150 minutes per week) has been shown to reduce RAAS activation in hypertensive patients 12. Stress reduction matters: chronic psychological stress activates the hypothalamic-pituitary-adrenal axis, which cross-talks with RAAS signaling and can sustain aldosterone elevation.

How to Raise Aldosterone

Raising aldosterone is rarely a standalone therapeutic goal. When levels are low due to primary adrenal insufficiency, fludrocortisone replacement (0.05 to 0.2 mg daily) directly replaces the missing mineralocorticoid 9. Dose titration uses clinical endpoints: resolution of orthostatic symptoms, normalization of serum potassium, and a plasma renin activity in the upper-normal range.

For functional hypoaldosteronism without frank adrenal disease, the approach targets root causes. Chronic licorice root consumption (glycyrrhizin) inhibits 11-beta-hydroxysteroid dehydrogenase type 2, mimicking aldosterone's effect but not raising measured aldosterone. It is not a substitute for medical treatment. Ensuring adequate sodium intake (not restricted below physiologic need), managing chronic stress, and supporting overall adrenal function with adequate sleep (7 to 9 hours), vitamin C (200 to 500 mg daily), and pantothenic acid are commonly used strategies in functional medicine, though randomized trial data supporting these interventions for aldosterone-specific endpoints remains limited.

Hyporeninemic hypoaldosteronism in diabetic patients may improve with better glycemic control. Fludrocortisone at low doses (0.05 to 0.1 mg daily) is sometimes used off-label for persistent hyperkalemia in this population, though loop diuretics or sodium bicarbonate are more common first-line options 8.

Testing Protocol: How to Get an Accurate Aldosterone Result

Proper sample collection is the single biggest determinant of a usable aldosterone result. The Endocrine Society guideline specifies the following protocol for ARR screening 2:

Medication washout. Discontinue spironolactone and eplerenone for at least 4 weeks. Withdraw ACE inhibitors, ARBs, beta-blockers, and dihydropyridine calcium channel blockers for at least 2 weeks, if safe. Verapamil slow-release and alpha-blockers (doxazosin, prazosin) may be used for blood pressure control during the washout period, as they minimally affect the ARR.

Sodium status. The patient should consume an unrestricted sodium diet for at least 3 days before the test. Severe sodium restriction raises aldosterone and renin, potentially masking an elevated ratio.

Posture. For a standard upright sample, the patient should be ambulatory for at least 2 hours before the blood draw. The sample should be collected with the patient seated for 5 to 15 minutes.

Timing. Draw between 8:00 and 10:00 AM. Aldosterone has a circadian rhythm that peaks in the early morning.

Potassium. Hypokalemia suppresses aldosterone secretion and can cause false-negative ARR results. Correct potassium to above 4.0 mEq/L before testing.

Confirmatory tests for a positive ARR screen include the oral sodium loading test (3-day high-sodium diet followed by 24-hour urine aldosterone; a value above 12 mcg/24 hours confirms PA), the intravenous saline infusion test (2 liters of normal saline over 4 hours; post-infusion aldosterone above 10 ng/dL confirms PA), and the fludrocortisone suppression test 2.

When to Retest and What to Do Next

Retest aldosterone if the initial result was collected under suboptimal conditions (wrong posture, interfering medications, uncorrected hypokalemia) or if clinical suspicion remains high despite a negative screen. The Endocrine Society specifically warns against excluding PA based on a single ARR result when pre-test probability is high 2.

For patients with confirmed PA, adrenal CT is the initial imaging study, followed by adrenal vein sampling (AVS) in surgical candidates to lateralize aldosterone excess. The SPARTACUS trial (N=200) compared CT-based treatment decisions to AVS-guided decisions and found similar blood pressure outcomes at one year, though AVS remains the recommended standard for patients over 35 years old due to the prevalence of non-functioning adrenal incidentalomas that can confound CT interpretation 13.

For patients whose aldosterone is technically "normal" but functionally suboptimal, serial testing every 3 to 6 months alongside a symptom diary (tracking blood pressure, energy, orthostatic tolerance, and salt cravings) builds a longitudinal picture that a single snapshot cannot provide. Pair each aldosterone measurement with renin, a basic metabolic panel, and a spot urine sodium-to-creatinine ratio to contextualize the result.