LH Urine ELISA

Intended Use
The DRG LH-Urine ELISA is an enzyme immunoassay for the quantitative in vitro diagnostic measurement of Luteinizing hormone (LH) in urine. This test is used to detect the midcycle LH surge in urine, which is an aid in predicting the time of ovulation.

Summary and Explanation
Luteinizing hormone (LH) is produced in both men and women by gonadotropic cells in the anterior pituitary gland in response to luteinizing hormone-releasing hormone (LH-RH or Gn-RH), which is released by the hypothalamus [1][2].

LH is also called interstitial cell-stimulating hormone (ICSH) in men. LH is a heterodimeric glycoprotein with a molecular weight of approximately 30 kDa. The protein dimer contains 2 glycopeptidic subunits, labeled alpha and beta subunits that are non-covalently associated [4]. While the LH alpha subunit is identical to that found in human thyroid-stimulating hormone (TSH), follicle stimulating hormone (FSH), and human chorionic gonadotropin (hCG), the beta subunit differs between these hormones [2][4]. The basal secretion of LH in men is episodic and has the primary function of stimulating the interstitial cells (Leydig cells) to produce testosterone. The variation in LH concentrations in women is subject to the complex ovulatory cycle of healthy menstruating women, and depends upon a sequence of hormonal events along the gonado-hypothalamic-pituitary axis. The decrease in progesterone and estradiol levels from the preceding ovulation initiates each menstrual cycle [5]. As a result of the decrease in hormone levels, the hypothalamus increases the secretion of gonadotropin-releasing factors (GnRF), which in turn stimulates the pituitary to increase FSH production and secretion [4]. The rising FSH levels stimulate several follicles during the follicular phase, one of these will mature to contain the egg. As the follicle develops, estradiol is secreted, peaking by day 12 or 13 of a normal cycle. LH is released as a result of this rapid increase of estradiol because of direct stimulation of the pituitary and increasing GnRF and FSH levels [2][5]. This "LH surge" triggers ovulation approximately 12 to 18 hours after LH reaches a maximum level. This not only releases the egg from the follicle, but also initiates the conversion of the residual follicle into the corpus luteum which secretes progesterone and estrogen - two negative feedback regulators of LH on the hypotalamic-pituitary axis [3][4][5][6][7][8]. The corpus luteum regresses if pregnancy does not occur, and the corresponding drop in progesterone and estradiol levels results in menstruation.

If pregnancy occurs, LH levels will decrease, and luteal function will instead be maintained by the action of hCG, a hormone very similar to LH but secreted from the new placenta. hCG causes the corpus luteum to continue producing progesterone and estradiol. In the differential diagnosis of hypothalamic, pituitary, or gonadal dysfunction, assays of LH concentration are routinely performed in conjunction with FSH assays since their roles are closely interrelated. Furthermore, the hormone levels are used to determine menopause, pinpoint ovulation, and monitor endocrine therapy.

For concrete data please consult the Instruction for Use in the download box on the top right side.