Leptin, Serum

Leptin, Serum

Number
	146712
CPT
	83520
Specimen
	Serum or plasma
Volume
	0.2 mL
Minimum Volume
	0.1 mL (Note: This volume does not allow for repeat testing.)
Container
	Red-top tube, gel-barrier tube, or lavender-top (EDTA) tube
Collection
	Transfer serum or plasma from cells and transfer to a plastic transport tube.
Storage Instructions
	Refrigerate at 2°C to 8°C. *Stable* for up to 7 days.
Causes for Rejection
	Gross hemolysis; gross lipemia
Reference Interval
	Nonobese, healthy adults Male: 0.5-13.8 ng/mL Female: 1.1-27.5 ng/mL Obese patients [corrected for body mass index (BMI)] Male: leptin = 1.5 (BMI) - 34 Female: leptin = 2.1 (BMI) - 29
Use
	Assessment of obesity, delayed puberty, and infertility
Limitations
	This procedure may be considered by Medicare and other carriers as investigational and, therefore, may not be payable as a covered benefit for patients.
Methodology
	Enzyme immunoassay (EIA)
Additional Information
	Leptin is a 16 kilodalton protein that was first identified when it was cloned in 1994.^1,2 Humans and mice with defects in the gene that codes for leptin, referred to as the obese or ob gene, tend to become morbidly obese.² Obese mice with the ob/ob defect lose weight when treated with exogenous leptin.² Leptin is produced primarily by white adipose tissue and blood levels correlated with body fat stores.^2,3 Increased leptin levels stimulate the central nervous system to reduce appetite and increase energy expenditure.^2,3 Leptin is thought to play an important role in the body's response to food deprivation or starvation.^3,4 Ongoing research indicates that leptin is also involved in a diverse array of physiologic functions beyond control of food intake and energy expenditure.^2,3 A role for leptin has been implicated in the control of angiogenesis, hematopoiesis, immunity and bone formation, and a number of other functions.² Leptin is thought to play a role in normal sexual development and in reproduction.^4,5 Humans and mice with genetic absence of leptin fail to complete puberty and increased leptin levels in mice lead to early puberty.⁴ Studies also suggest that leptin levels affect fertility in females and may be involved in the development of normal pregnancy.^4,5 During pregnancy, the placenta produces leptin, and maternal circulating levels during the second and third trimesters are approximately twice the level of the nonpregnant state.^4,5
Footnotes
	Zhang Y, Proenca R, Maffei M, et al, “Positional Cloning of the Mouse Obese Gene and Its Human Homologue,” Nature, 1994, 372(6505):425-32. Trayhurn P, Hoggard N, Mercer JG, et al, “Leptin: Fundamental Aspects,” Int J Obes Relat Metab Disord, 1999, 23(Suppl 1):22-8 (review). Van Gaal LF, Wauters MA, Mertens IL, et al, “Clinical Endocrinology of Human Leptin,” Int J Obes Relat Metab Disord, 1999, 23(Suppl 1):29-36. Reitman ML, Bi S, Marcus-Samuels B, et al, “Leptin and Its Role in Pregnancy and Fetal Development - An Overview,” Biochem Soc Trans, 2001, 29(Pt 2):68-72 (review). Hoggard N, Haggarty P, Thomas L, et al, “Leptin Expression in Placental and Fetal Tissues: Does Leptin Have a Functional Role?” Biochem Soc Trans, 2001, 29(Pt 2):57-63 (review)