Progesterone

Progesterone (4-pregnen-3.20-dione) is one of the 21-carbon steroids secreted by the corpus luteum of the ovary in females during the normal menstrual cycle. It is also produced in low concentrations by the adrenal cortex in both males and females. In pregnancy, the placenta is the major source of progesterone after the seventh gestational week.

Progesterone has two main biological functions. First, it transforms the estrogen-stimulated endometrium into the secretory phase, which allows implantation of the fertilized ovum. Secondly, it sustains pregnancy by decreasing uterine contractility.

During the follicular phase, progesterone concentrations are low prior to the mid-cycle gonadotropin surge. Progesterone concentrations in the range 0.3–3.5 nmol/L have been measured the day before the LH peak. Immediately after the LH surge, concentrations begin to rise rapidly and reach maximum levels at the middle of the luteal phase. During a normal luteal phase, progesterone concentrations are between 3.9–80 nmol/L and the peak level should exceed 25 nmol/L.

Measurements of maternal progesterone levels have been suggested for the clinical assessment of threatening abortion, hydatidiform mole, and rhesus isoimmunization.

: Store/transport at 15–30°C for ≤8 hours; 2–8°C for ≤48 hours; freeze at ≤ –20°C if testing is delayed. Avoid repeated freeze–thaw cycles.

Hemolyzed or unseparated specimens.

Enhanced chemiluminescence

Female:

• Mid-Follicular Phase: 31–1.52 ng/mL
• Mid-Luteal Phase: 16–18.56 ng/mL
• Postmenopausal: <0.7 ng/mL

Pregnancy:

• First Trimester: 73–50.74 ng/mL
• Second Trimester: 41–445.30 ng/mL

Male:

• 14–2.06 ng/mL

• Cooke, I.D. (1976): In Loraine, J.A. and Bell, E.T. (eds): Hormone assays and their clinical application. Churchill Livingstone, Edinburgh, London and New York, 4th edition, pp 447-518.

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