13N-ammonia, applied rectally, after absorption and transportation visualises the liver. After release of 13N-aminoacids and 13N-urea by the liver, 13N-activity can be measured over other organs. In patients with porta-systemic shunts, 13N-ammonia will appear in the systemic circulation as well. In 16 controls and 26 patients with cirrhosis, activities were measured for 20 minutes over liver, spleen, heart, lungs and forearm. In all subjects, the liver was visualised within a minute, in some patients with cirrhosis faintly, however. Release by the liver of 13N-ammonia metabolites started within a few minutes. Liver/heart activity ratios proved to be more discriminating between the control- and the cirrhosis group than liver/lung and liver/spleen ratios. In the control group, the 20 minutes' liver/heart ratio was most suitable for determining the normal range. The lower normal level was found to be 2.25. Fourteen of the 26 patients with cirrhosis had a normal, 12 an abnormally low 20 minutes' liver/heart ratio.

Adult↗

PubMedDate not supplied

Rectal 13N-ammonia test (13N-liver/heart ratio), hepatic sinusoidal pressure and prevailing portal flow direction in cirrhosis of the liver.

The 20 minutes' liver/heart activity ratio after rectal administration of 13N-ammonia was abnormally low (less than 2.25) in 12 of 26 patients with cirrhosis of the liver. An abnormal conventional rectal arterial ammonia test (porta-systemic shunts), an abnormally low urea index (prevailing hepatofugal portal venous flow direction), marked portal hypertension (hepatic sinusoidal pressure greater than or equal to 8 mm Hg), ascites and extreme enlargement of the spleen occurred significantly more often in the patients with an abnormally low 13N-liver/heart ratio than in those with a ratio greater than or equal to 2.25. There was no correlation between the 13N-liver/heart ratio and absence or presence of oesophageal varices. The non-invasive rectal 13N-ammonia test appears to be an easy to perform, informative test in cirrhosis of the liver.

Adult↗