LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report.
This case report tracked a single 25-year-old recreationally active male who self-administered LGD-4033 (a selective androgen receptor modulator) and MK-677 (a growth hormone secretagogue) daily for five weeks. Blood work and body composition (via DXA) were collected before, during, and after the cycle, while muscular strength and skeletal muscle androgen-related biomarkers were assessed during the cycle and compared cross-sectionally against data from non-using trained males. The study observed increases in total body mass, lean mass, and fat mass during the cycle, alongside adverse changes in bone mineral content and density, serum lipids (notably a 40% rise in LDL and a 36% drop in HDL), and liver enzymes (ALT rose over 200%). Total and free testosterone and sex hormone-binding globulin fell markedly during the cycle. Most biomarkers returned toward baseline post-cycle, though total cholesterol, LDL, total fat mass, and bone area did not fully recover. Follicle-stimulating hormone remained below clinical reference ranges even post-cycle. Compared with non-users, the subject showed higher intramuscular testosterone and dihydrotestosterone but lower androgen receptor content, alongside greater strength. Key limitations include the single-subject design, lack of a control group, and reliance on cross-sectional comparisons for intramuscular and strength data, making causal inferences unreliable.
Why this grade: A single-subject case report with no randomization, no control group, and cross-sectional comparisons for key outcomes; findings cannot be generalized despite being conducted in a human.
New findings What is the main observation in this case? Co-administration of LGD-4033 and MK-677 increased body mass, lean mass and fat mass, while negatively impacting bone, serum lipids, liver enzymes, testosterone (total and free) and, probably, follicle-stimulating hormone. What insights does it reveal? Our cross-sectional data imply that these compounds might alter intramuscular androgenic hormone and receptor concentrations along with promoting muscular strength, when compared with previously published data from trained males. Abstract LGD-4033, a selective androgen receptor modulator, and MK-677, a growth hormone secretagogue, are being used increasingly amongst recreationally active demographics. However, limited data exist describing their effects on health- and androgen-related biomarkers. The purpose of this case study was to determine changes in body composition and biomarkers during and after continued co-administration of LGD-4033 and MK-677. We also aimed to examine muscular strength and intramuscular androgen-associated biomarkers relative to non-users. A 25-year-old male ingested LGD-4033 (10 mg) and MK-677 (15 mg) daily for 5 weeks. Blood and body composition metrics were obtained pre-, on- and post-cycle. One-repetition maximum leg and bench press, in addition to intramuscular androgens and androgen receptor content, were analysed on-cycle. We observed pre- to on-cycle changes in body composition (body mass, +6.0%; total lean body mass, +3.1%; trunk lean body mass, +6.6%; appendicular lean body mass, +4.3%; total fat mass, +15.4%; trunk fat mass, +2.8%; and appendicular fat mass, +14.8%), bone (bone mineral content, -3.60%; area, -1.1%; and bone mineral density, -2.1%), serum lipid-associated biomarkers (cholesterol, +14.8%; triglycerides, +39.2%; low-density lipoprotein-cholesterol, +40.0%; and high-density lipoprotein-cholesterol, -36.4%), liver-associated biomarkers (aspartate aminotransferase, +95.8%; and alanine aminotransferase, +205.0%) and androgen-associated biomarkers (free testosterone, -85.7%; total testosterone, -62.3%; and sex hormone-binding globulin, -79.6%); however, all variables returned to pre-cycle values post-cycle, apart from total fat mass, appendicular fat mass, bone area, total cholesterol and low-density lipoprotein-cholesterol. Follicle-stimulating hormone was below clinical reference values on- (1.2 IU/L) and post-cycle (1.3 IU/L). Intramuscular androgen receptor (-44.6%), testosterone (+47.8%) and dihydrotestosterone (+34.4%), in addition to one-repetition maximum leg press and bench press (+39.2 and +32.0%, respectively), were different in the case subject compared with non-users. These data demonstrate that LGD-4033 and MK-677 increase several body composition parameters, whilst negatively impacting bone and several serum biomarkers. Given the sparsity of data in recreationally using demographics, further research is warranted to elucidate the acute and chronic physiological effects of these anabolic agents.
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