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

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or secondary

aldosteronism Hyperaldosteronism is a medical condition wherein too much aldosterone is produced by the adrenal glands, which can lead to lowered levels of potassium in the blood (hypokalemia) and increased hydrogen ion excretion (alkalosis). This cause of mi ...

Physiological principle

The

steroid hormone A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into two classes: corticosteroids (typically made in the adrenal cortex, hence ''cortico-'') and sex steroids (typically made in the gonads or placenta). Wi ...

aldosterone Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays a c ...

stimulates the reabsorption of

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...

and the excretion of

potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...

in the distal tubuli and the

collecting tubes The collecting duct system of the kidney consists of a series of tubules and ducts that physically connect nephrons to a minor calyx or directly to the renal pelvis. The collecting duct system is the last part of nephron and participates in elect ...

of the

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...

s. Calculating SUSPUP and/or SUSPPUP helps to determine the intensity of

mineralocorticoid Mineralocorticoids are a class of corticosteroids, which in turn are a class of steroid hormones. Mineralocorticoids are produced in the adrenal cortex and influence salt and water balances (electrolyte balance and fluid balance). The primary mi ...

signalling, which may be helpful in the differential diagnosis of

hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...

and hypokalaemia.

Preconditions of testing

Sodium and potassium concentrations have to be determined in serum and spot

urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra. Cel ...

probes that have been obtained simultaneously or within a short time interval between.

Calculation

SUSPUP = a⁺sub>Serum / a⁺sub>Urine / ⁺sub>Serum / ⁺sub>Urine SUSPPUP = a⁺sub>Serum / a⁺sub>Urine / ⁺sub>Serum² / ⁺sub>Urine

Interpretation

Reference ranges are 3.6–22.6 for SUSPUP and 0.6–5.3 for SUSPPUP. Increased values support the hypothesis of increased mineralocorticoid stimulation of the distal tubules and collecting tubes, i.e. in cases of hyperaldosteronism. 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 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.{{cite journal , last1=Knoop , first1=H , last2=Knoop , first2=U , last3=Behr , first3=J , last4=Heyer , first4=CM , last5=Kuert , first5=S , last6=Roggenland , first6=D , last7=Suermann , first7=M , last8=Dietrich , first8=JW , title=Syndrome of inadequate antidiuretic hormone secretion in pulmonary tuberculosis - a therapeutic challenge. , journal=Pneumologie (Stuttgart, Germany) , date=April 2013 , volume=67 , issue=4 , pages=219–22 , doi=10.1055/s-0032-1326101 , pmid=23420227, doi-access=free

References

Adrenal gland disorders Human homeostasis Static endocrine function tests