Serum cortisol in women users of subdermal levonorgestrel implants
Related Experiment Video
Updated: Sep 29, 2026

Cortisol Measurement in Koala (Phascolarctos cinereus) Fur
Published on: August 23, 2019
Abstract:
The aim of this study was to reveal changes in serum cortisol levels in users of subdermal levonorgestrel implants (Norplant). The study was undertaken on 18 regularly menstruating females subdermally implanted with 6 silastic rods, each containing 34 +or- 2 mg levonorgestrel, between days M0-M+4 of the menstrual cycle. Venous blood samples were collected between 10:00 and 11:00 a.m. under basal conditions, before and 1, 6, and 12 months after implantation. Sera were analyzed for cortisol by radioimmunoassay procedures. Mean +or- S.E.M. cortisol levels were 15.94 +or- 1.23, 10.20 +or- 0.84, 11.21 +or- 1.14, and 11.14 +or- 1.05 mcg prior to and 1, 6, and 12 months after implantation, respectively. All postimplantation values were significantly lower in comparison to basal levels. However, results obtained fell within the normal range of serum cortisol, with no subjects reporting symptoms of adrenocortical insufficiency.
Related Concept Videos
Hormones of the Adrenal Glands
The adrenal cortex, a powerhouse of hormone synthesis, generates over two dozen corticosteroid hormones. The zona glomerulosa produces mineralocorticoids, exemplified by aldosterone, influencing the electrolyte composition of body fluids. The synthesis of glucocorticoids such as cortisol and corticosterone...
Cushing Syndrome II: Pathophysiology
Hormonal Control of the Ovarian Cycle
Before puberty, the hypothalamus releases GnRH in a low frequency, low amplitude pulsatile manner. This along with the immature hypothalamic-pituitary-gonadal axis activity, results in low estrogen levels and the absence of a fully functional ovarian cycle. At puberty, GnRH secretion increases in both frequency and...
Hormonal Regulation of the Menstrual Cycle
At puberty, GnRH begins a pulsatile release pattern, which triggers the anterior pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The frequency and amplitude of GnRH pulses vary across the menstrual cycle, with faster pulses favoring LH release and slower pulses favoring FSH release.
Cushing Syndrome I: Introduction
Intrauterine Drug Delivery Systems

