Serum chorionic gonadotropin levels determined by radioreceptorassay and early diagnosis of pregnancy in the cynomolgus monkey (Macaca fascicularis).

The radioreceptorassay developed to determine serum luteinizing hormone level in the cynomolgus monkey was evaluated for its usefulness in early pregnancy diagnosis by the detection of serum chorionic gonadotropin (CG). Blood samples were collected at weekly intervals from the 1st to the 5th week after conception to determine changes in circulating levels of CG. In the pregnancy cases, serum CG levels increased to above 50 μg/ml in almost all animals.