SUSPUP and SUSPPUP explained

SUSPUP and SUSPPUP
Test Of:	Extent of hormonal stimulation of sodium absorption and potassium excretion in kidney's tubules and collecting tubes
Synonyms:	(serum sodium to urinary sodium to serum potassium to urinary potassium) and (serum sodium to urinary sodium to serum potassium^2 to urinary potassium)
Reference Range:	3.6–22.6 (SUSPUP) 0.6–5.3 (SUSPPUP)

SUSPUP (serum sodium to urinary sodium to serum potassium to urinary potassium) and SUSPPUP (serum sodium to urinary sodium to (serum potassium)² to urinary potassium) are calculated structure parameters of the renin–angiotensin-aldosterone system (RAAS). They have been developed to support screening for primary or secondary aldosteronism.^{[1] [2]}

Physiological principle

The steroid hormone aldosterone stimulates the reabsorption of sodium and the excretion of potassium in the distal tubuli and the collecting tubes of the kidneys. Calculating SUSPUP and/or SUSPPUP helps to determine the intensity of mineralocorticoid signalling, which may be helpful in the differential diagnosis of hypertension and hypokalaemia.

Preconditions of testing

Sodium and potassium concentrations have to be determined in serum and spot urine probes that have been obtained simultaneously or within a short time interval between.

Calculation

SUSPUP = (({{[Na)/(] _{Serum} ^{+}))/() }}SUSPPUP = (({{[Na)/(] _{Serum} ^{+}))/() }}

Interpretation

Reference ranges are 3.6–22.6 for SUSPUP and 0.6–5.3 for SUSPPUP.^[1]

Increased values support the hypothesis of increased mineralocorticoid stimulation of the distal tubules and collecting tubes, i.e. in cases of hyperaldosteronism.^[3] While these parameters have a high sensitivity for screening purposes their specificity may be inferior compared to aldosteron-to-renin ratio (ARR) and potassium concentrations^[4]

Both parameters may also be elevated in syndrome of inappropriate ADH secretion (SIADH), probably reflecting a compensatory mechanism, where the organism tries to maintain serum sodium concentrations by means of increased renin and/or aldosterone secretion.^[5]

References

1. Willenberg . HS . Kolentini . C . Quinkler . M . Cupisti . K . Krausch . M . Schott . M . Scherbaum . WA . The serum sodium to urinary sodium to (serum potassium)2 to urinary potassium (SUSPPUP) ratio in patients with primary aldosteronism. . European Journal of Clinical Investigation . January 2009 . 39 . 1 . 43–50 . 10.1111/j.1365-2362.2008.02060.x . 19067735. free .
2. Yin . GS . Zhang . SL . Yan . L . Li . F . Qi . YQ . Chen . ZC . Cheng . H . 联合应用血钾血钠和尿钾尿钠的综合指数在原发性醛固酮增多症筛查中的作用 [New index of using serum sodium and potassium and urine sodium and potassium jointly in screening primary aldosteronism in hypertensive patients]. . Zhonghua Yi Xue Za Zhi . 13 April 2010 . 90 . 14 . 962–6 . 20646645.
3. Balaş . M . Zosin . I . Maser-Gluth . C . Hermsen . D . Cupisti . K . Schott . M . Schinner . S . Knoefel . WT . Scherbaum . WA . Willenberg . HS . Indicators of mineralocorticoid excess in the evaluation of primary aldosteronism. . Hypertension Research . August 2010 . 33 . 8 . 850–6 . 10.1038/hr.2010.76 . 20520614. free .
4. Steichen . O . Blanchard . A . Plouin . PF . Assessment of serum sodium to urinary sodium divided by (serum potassium)² to urinary potassium as a screening tool for primary aldosteronism. . European Journal of Clinical Investigation . February 2011 . 41 . 2 . 189–94 . 10.1111/j.1365-2362.2010.02401.x . 20955208. 37407685 .
5. Knoop . H . Knoop . U . Behr . J . Heyer . CM . Kuert . S . Roggenland . D . Suermann . M . Dietrich . JW . Syndrome of inadequate antidiuretic hormone secretion in pulmonary tuberculosis - a therapeutic challenge. . Pneumologie (Stuttgart, Germany) . April 2013 . 67 . 4 . 219–22 . 10.1055/s-0032-1326101 . 23420227. free .