SUSPUP and SUSPPUP

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SUSPUP and SUSPPUP are simple indicators used to gauge how strongly the kidney’s sodium reabsorption and potassium excretion are influenced by the hormone aldosterone, a key part of the renin–angiotensin–aldosterone system (RAAS).

What they’re for
- They help screen for primary or secondary aldosteronism, conditions where aldosterone levels are too high and can cause high blood pressure and low potassium.
- They reflect the level of mineralocorticoid signaling in the distal parts of the kidney (the distal tubules and collecting ducts).

How they’re calculated (in practice)
- Blood (serum) and urine samples are collected at roughly the same time.
- Sodium and potassium levels are measured in both samples.
- These values are combined into two indices, SUSPUP and SUSPPUP, using specific formulas (the exact math is technical).

Reference ranges
- SUSPUP: 3.6–22.6
- SUSPPUP: 0.6–5.3

What elevated values mean
- Higher SUSPUP or SUSPPUP values support the possibility of increased aldosterone activity in the kidneys, such as in hyperaldosteronism.
- They are highly sensitive for screening but may be less specific than the aldosterone-to-renin ratio (ARR) and potassium levels.

Important notes
- Both indices can be elevated in other situations, including syndrome of inappropriate ADH secretion (SIADH), likely as the body’s compensatory response to maintain serum sodium.
- They are usually used alongside other tests rather than as a sole diagnostic measure.

Bottom line
SUSPUP and SUSPPUP are easy-to-measure, kidney-focused markers that help doctors assess aldosterone-related activity as part of evaluating high blood pressure and related electrolyte issues.