Progesterone, an ovarian steroid hormone secreted by the corpus luteum, causes thickening and secretory growth of the endometrium in preparation for implantation of the fertilized ovum. Progesterone levels, therefore, peak during the midluteal phase of the menstrual cycle. If implantation doesn’t occur, progesterone (and estrogen) levels drop sharply and menstruation begins about 2 days later.
During pregnancy, the placenta releases about 10 times the normal monthly amount of progesterone to maintain the pregnancy. Increased secretion begins toward the end of the first trimesterand continues until delivery. Progesterone prevents abortion by decreasing uterine contractions. Along with estrogen, progesterone helps prepare the breasts for lactation.
This radioimmunoassay is a quantitative analysis of plasma progesterone levels and provides reliable information about corpus luteum function in fertility studies and placental function in pregnancy. Serial determinations are recommended. Although plasma levels provide accurate information, a can also be monitored by measuring urine pregnanediol, a catabolite of progesterone. The ideal specimen for the test is heparinized plasma; non-icteric, non-hemolyzed, non-turbid serum.
The purpose of radioimmunoassay test for plasma is to assess corpus luteum function as part of infertility studies, to evaluate placental function during pregnancy and to aid in confirming ovulation; test results support basal body temperature readings.
You must explain the procedure to the patient before subjecting her to further testing. Note the date of last menstrual period/length of gestation.Do not register radioisotopes within 1 week before the test. It is important to check the patient’s history if she’s taking drugs that may interfere with test results, including progesterone and estrogen. Inform the patient that the test may be repeated at specific times coinciding with phases of her menstrual cycle or with each prenatal visit. Inform the patient that she need not restrict foods and fluids.
Obtain a venous blood sample. Serum is needed for the test. Remember that the test should include gender, day of last menstrual period, and length of gestation in women. Remember that urine levels may be done, but serum is preferred.Be aware that β-hCG may be ordered at the same time. Apply direct pressure to the venipuncture site until bleeding stops. If hematoma develops at the venipuncture site, apply warm compress.
During menstruation, normal progesterone values are:
- follicular phase: <150>
- luteal phase: 300-1,200 ng/dl (SI, 10-40nmol/L)
During pregnancy, normal progression values are:
- First trimester: 1,500-5,000 ng/dl (SI, 50-160 nmol/L
- Second and third trimester: 8,000-20,000 ng/dl (SI, 250-650 nmol/L)
Normal values in menopausal women
- 10-22 ng/dl (SI, 0-2 nmol/L)
Elevated progesterone levels may indicate ovulation, luteneizing tumors, ovarian cysts that produce progesterone or adrenocortical hyperplasia and tumors that produce progesterone along with steroidal hormones.Low progesterone levels are associated with amenorrhea due to several causes (such as panhypopituitarism and gonadal dysfunction), eclampsia, threatened abortion and fetal death.
- A Manual of Laboratory and Diagnostic Tests 7th Edition By: Frances Fischbach
- Prof. Guide to Diagnostic Tests