Using radioimmunoassay, immunoreactive SP (iSP) has been measured in the plasma of
162 hospital patients with various disorders and in the plasma of 67 pregnant women.
In pregnancy, iSP was undetectable in 40% women as compared to 12% in other hospital
patients. The mean iSP plasma level in pregnancy was 37.8 ± 4.6 (SEM) as compared
to 77.1 ± 4.9 (SEM) pg/ml in other hospital patients. These results support earlier
observations based on bioassay, suggesting that the blood of pregnant women contains
higher concentrations of a SP-inactivating factor. Of the hospital patients, elevated
levels of iSP were found in patients with chronic leukaemia, in one patient with a
basaloid carcinoma of the anus, and in one patient with toxic liver damage and pancreatic
insufficiency. No correlation was found between thyroid function and iSP plasma levels.
ISP plasma levels in various gastrointestinal disorders were similar to those found
in normal subjects.
Substance P - Radioimmunoassay - Pregnancy - Malignant Tumors - Gastrointestinal Disorders
- Thyroid Disorders - Cystic Fibrosis
