Aldosterone

Overview

Aldosterone is a steroid hormone produced by the zona glomerulosa of the adrenal cortex, responsible for maintaining salt balance, water balance, blood volume, and blood pressure. As described in the document (pages 2–3), it acts primarily on the kidneys to increase sodium reabsorption and potassium excretion, while working alongside ADH, which controls water reabsorption. Both hormones are released when blood pressure is low, forming a coordinated response to maintain circulatory stability.

Biosynthesis occurs through the enzymatic conversion of cholesterol to deoxycorticosterone and ultimately to this. Regulation is tightly controlled by serum potassium and the renin-angiotensin system, illustrated in the pathway diagram on page 6. The testing includes assays such as ELISA, UPLC, UPLC–MS/MS, RIA, and CLIA (page 8), using either plasma or 24-hour urine samples (page 9). It plays a crucial diagnostic role in evaluating disorders like hyperaldosteronism and adrenal insufficiency.

Symptoms

Symptoms prompting the testing relate to abnormalities in salt balance, potassium levels, and blood pressure. The indications list on page 7 outlines the key clinical features.

Common Symptoms of High Aldosterone

1. High blood pressure is often resistant to treatment
2. Muscle weakness, cramps, or spasms
3. Low potassium levels are seen on lab tests
4. High sodium levels
5. Fatigue and headache
6. Arrhythmia (irregular heartbeat)
7. Increased thirst and urination

These symptoms result from excessive sodium retention and potassium loss.

Symptoms of Low Aldosterone

Based on the causes listed on page 16, symptoms may include:

1. Persistent fatigue
2. Low blood pressure
3. Dizziness
4. Salt craving
5. Hyperkalemia (high potassium)
6. Dehydration symptoms

Symptoms reflect the body’s inability to maintain electrolyte and fluid balance.

Causes

The document divides causes of abnormal aldosterone into high and low categories.

Causes of High Aldosterone (Hyperaldosteronism)

(Page 15)

1. Primary aldosteronism (Conn’s syndrome)
2. Adrenal adenomas
3. Unilateral adrenal hyperplasia
4. Adrenocortical carcinomas
5. Heart failure
6. Liver disease
7. Renal artery disease
8. Genetic disorders, including
   1. Familial Hyperaldosteronism Types I–IV
   1. PASNA syndrome

These conditions trigger excessive aldosterone production, leading to sodium retention, water retention, and potassium depletion.

Causes of Low Aldosterone

(Page 16)

1. Primary adrenal insufficiency (Addison’s disease)
2. Autoimmune diseases
3. Infections and infiltrative disorders
4. Enzyme deficiencies (e.g., congenital adrenal hyperplasia)
5. Medications such as heparin and ACE inhibitors
6. Diabetes and kidney failure, which impair the renin–angiotensin system

These causes reduce hormone synthesis or disrupt regulatory pathways.

Risk Factors

Risk factors reflect clinical scenarios where aldosterone testing becomes essential.

1. Persistent or Severe Hypertension

Patients with difficult-to-control blood pressure may have primary or secondary aldosteronism (page 17).

2. Electrolyte Imbalance

Low potassium or high sodium levels (page 7) increase the likelihood of aldosterone disorders.

3. Adrenal Gland Disorders

Presence of adenomas, hyperplasia, or carcinoma increases the risk of abnormal aldosterone production.

4. Cardiovascular and Metabolic Diseases

According to the table on page 17:

1. Heart failure
2. Cardiovascular disease (myocardial fibrosis, hypertrophy)
3. Metabolic syndrome and diabetes

5. Renal System Disorders

Renal artery disease or impaired renin production contributes to excess or deficiency.

6. Genetic Predisposition

Familial hyperaldosteronism types listed on page 15 pose a high risk for early-onset hypertension and electrolyte abnormalities.

Prevention

Prevention in the context of aldosterone testing focuses on avoiding diagnostic errors, supporting accurate evaluation, and minimizing complications from hormone imbalance.

1. Correct Sample Collection

(Page 9)

1. For 24-hour urine: instruct patient carefully, add 10 ml N/10 HCl as preservative, measure volume accurately.
2. For plasma: collect 3 mL of blood in an EDTA tube and separate promptly.

2. Proper Patient Preparation

The suppression test (page 10) requires a high-salt diet before urine collection to evaluate aldosterone responsiveness. Inadequate preparation may distort results.

3. Review Medications Before Testing

Certain drugs (page 16), such as ACE inhibitors or heparin, may suppress aldosterone; adjusting therapy prevents inaccurate interpretation.

4. Adjust Diagnostic Interpretation With ARR

The aldosterone-renin ratio (page 12) must be interpreted considering posture, medication use, and clinical condition to prevent misclassification.

5. Monitor At-Risk Patients Early

Early testing for those with resistant hypertension, adrenal masses, or unexplained electrolyte changes prevents disease progression.

6. Supportive Management of Underlying Disorders

Treating heart failure, kidney disease, or adrenal disorders can prevent worsening aldosterone imbalance.