Somatropin

Limits on what this shows

• Key negative/null findings: Sinha et al. 2014 is itself the key null finding: no measurable mitochondrial oxidative phosphorylation deficit in the actual treated human population.
• At-risk subgroups: None identified in human data.

Regulatory status

Not addressed in the FDA label.

Population evidence

Sinha, Hollingsworth, Ball, Cheetham (2014), Clin Endocrinol (Oxf), PMID 23711232. Cross-sectional study, n=65: 22 untreated GHD adults, 23 GH-treated GHD adults (this drug's population), 20 healthy controls. Phosphorus-31 MRS measurement of skeletal-muscle phosphocreatine (PCr) recovery half-time, a direct marker of mitochondrial oxidative phosphorylation capacity, and pH recovery. No significant difference across the three groups (P=0.53 for mitochondrial function, P=0.38 for pH recovery); no correlation with IGF-1.

Mechanism

Plausibility only, from animal literature: GH receptor expression/deletion studies in chicken bone marrow mesenchymal cells (Zhao et al. 2022, PMID 35350383) and chicken tissue (Hu et al. 2019, PMID 30935132) link GH receptor signaling to mitochondrial biogenesis and function; titles and citations were confirmed via a PubMed listing, but full findings were not independently opened during this review, and both models are non-mammalian.

Counter-evidence held on record

A single case report (Rocha et al. 2015, PMID 25781523) described reduced mitochondrial complex II activity in a child with both growth hormone deficiency and a separate, underlying mitochondrial disease. This describes comorbidity in a patient whose GHD likely arose from the mitochondrial disease, not evidence that somatropin treatment harms mitochondria, and is excluded as supporting evidence for this entry (see Sources). The only available human study of the treated population found no deficit. This entry documents that a mechanistic hypothesis has been explored in non-human models, not a confirmed human risk.

Limits on what this shows

• Key negative/null findings: Nitric oxide showed no significant change; this is one small, unreplicated study.
• At-risk subgroups: None identified.

Regulatory status

Not addressed in the FDA label.

Population evidence

Kościuszko et al. (2024), Research Square preprint (not yet peer-reviewed), DOI 10.21203/rs.3.rs-4883080/v1. Prospective observational study, n=15 adult-onset GHD patients started on rhGH (Omnitrope = somatropin), followed at baseline, 6, and 12 months. Total oxidative capacity (TOC) fell at 6 and 12 months (P=0.02, P=0.04); total antioxidant capacity (TAC) rose at 12 months (P=0.02); endothelin-1 and ADMA also fell.

Mechanism

Not fully elucidated in the source; authors framed the change as part of a broader cardiovascular-risk-reduction effect of correcting GHD.

Counter-evidence held on record

No study located shows somatropin worsening oxidative stress markers in humans. This is a reverse-direction (potentially protective), not depleting, signal, and it rests on one small, unreplicated, non-peer-reviewed preprint. It should not be read as an established protective claim, only as the best currently located evidence.

Limits on what this shows

• Key negative/null findings: Soluble transferrin receptor, the marker most specific to functional iron deficiency, did not significantly change in the same cohort (Vihervuori 1997), indicating a store-level shift rather than confirmed tissue-level iron deficiency. See Overlap map for this entry's relationship to Oxygen delivery/utilization.
• At-risk subgroups: Children undergoing GH-induced accelerated or catch-up growth, where iron demand from expanding red-cell mass is highest; not established for adult GHD replacement at physiological maintenance doses.

Regulatory status

Not addressed in the FDA label; iron status monitoring is not a labeled requirement.

Population evidence

Vihervuori, Cook, Siimes (1997), Acta Paediatr, DOI 10.1111/j.1651-2227.1997.tb08939.x: n=35 children with short stature given GH treatment, followed over 6 months of GH-driven accelerated growth. Serum ferritin decreased and serum transferrin increased over the treatment period; soluble transferrin receptor, a marker more specific to functional (tissue-level) iron deficiency, showed minimal change. Companion study, Vihervuori et al. (1996), Blood 88(10) [conference/journal report], n=40 short children on rhGH followed 12 months: hemoglobin rose overall by 0.42 g/dL (up to 1.32 g/dL in the skeletal-dysplasia subgroup), correlating with serum IGF-I and IGFBP-3 (r=0.37-0.52, P=.001-.037) but not with erythropoietin (P=.48), indicating GH/IGF-1-driven, erythropoietin-independent erythropoiesis as the mechanism increasing iron demand.

Mechanism

Named: GH/IGF-1 directly stimulates bone-marrow erythropoiesis independent of erythropoietin, increasing red-cell production and consuming iron stores faster than the ferritin pool can passively replace, without necessarily producing overt anemia.

Counter-evidence held on record

No study located found iron overload or a stable/unaffected iron profile with GH treatment; direction (increased utilization) is consistent across the two Vihervuori studies, which describe the same erythropoiesis-stimulation mechanism in overlapping accelerated-growth cohorts (see Overlap map). Exact p-values for the ferritin/transferrin changes were not independently confirmed beyond the source's own indexed abstract. This supports monitoring iron status during periods of rapid GH-induced growth, not empiric iron supplementation. No iron dose is recommended here; iron repletion without a measured deficit carries its own overload risk and should only follow direct laboratory confirmation and prescriber guidance.

Limits on what this shows

• Key negative/null findings: Pankratova 2015 is the key null finding: ceruloplasmin unchanged after 12 months of the actual modern drug class (recombinant GH) in the pediatric GHD population, the most clinically relevant of the three sources.
• At-risk subgroups: Cannot be determined from the available evidence.

Regulatory status

Not addressed in the FDA label.

Population evidence

Brandão-Neto et al. (1988), Braz J Med Biol Res, PMID 3179576: n=7 healthy adults given a single 60-minute IV infusion of human GH (era predates or coincides with the shift from pituitary-derived to recombinant hGH). At the lower dose (0.2 mg), plasma copper decreased while zinc, calcium, and magnesium rose; at the higher dose (1.0 mg), the effects reversed direction. Aihara et al. (1985), J Pediatr Gastroenterol Nutr, PMID 4032177, DOI 10.1002/j.1536-4801.1985.tb08917.x: cohort of GHD patients on hGH treatment and acromegaly patients post-pituitary-surgery (pituitary-derived hGH era); reported that "copper, manganese, and selenium levels also shifted with hGH status changes," but the specific direction and magnitude for copper could not be confirmed from the sources accessible during this review (see access notes). Pankratova et al. (2015), PeerJ 3:e1055, DOI 10.7717/peerj.1055: n=11 treatment-naive GHD children given 12 months of recombinant GH, the modern drug class; ceruloplasmin, the principal copper-transport/status marker, showed no statistically significant change after 12 months of therapy, though a nonsignificant trend was noted.

Mechanism

Named but unresolved in direction: acute hGH dosing appears to acutely mobilize or redistribute plasma copper in a dose-dependent, non-monotonic pattern (Brandão-Neto); no confirmed mechanism or direction for chronic treatment.

Counter-evidence held on record

The one study using actual modern recombinant GH and a real chronic copper-status marker (ceruloplasmin) found no significant change. The acute-effect study used a single IV bolus, not the chronic subcutaneous dosing somatropin actually uses, and its two doses produced opposite directions of effect, which limits its relevance to real-world dosing. Mechanistic and historical evidence only; no confirmed chronic copper deficit from growth hormone therapy. Not a basis for copper supplementation.

Limits on what this shows

• Key negative/null findings: No human data; no study administering somatropin and measuring microbiome composition was found despite search.
• At-risk subgroups: Cannot be determined from available evidence.

Regulatory status

Not addressed in the FDA label; no microbiome monitoring is recommended.

Population evidence

Yu, Wang, Zhang et al. (2023), Gut Microbes, DOI 10.1080/19490976.2023.2221098. Mouse model with hepatic growth hormone receptor (GHR) gene deletion — i.e., loss of GH signaling, the opposite manipulation from somatropin administration — found altered gut microbial composition mediated by changed bile-acid metabolism.

Mechanism

Named but indirect: hepatic GH signaling affects bile-acid synthesis and composition, which in turn shapes the gut microbial community. Shown by removing GH signaling, not by adding exogenous GH.

Counter-evidence held on record

None found in either direction in humans. Direction of effect for actual somatropin therapy (receptor agonism, not receptor loss) cannot be inferred from a knockout model. Treat as biological plausibility only.

Limits on what this shows

• Key negative/null findings: Not confirmable from the access available during this review.
• At-risk subgroups: Children/adults with GHD-related anemia specifically, not the general GHD population.

Regulatory status

Not a labeled indication; GHD is independently recognized as a cause of mild normocytic-normochromic anemia via reduced GH/IGF-1 stimulation of bone-marrow red-cell production.

Population evidence

Miniero, Altomare, Rubino et al. (2012), J Pediatr Hematol Oncol 34(6):407-11, PMID 22584781. Title, journal citation, and a search-result snippet were confirmed via PubMed, establishing that the study examined children with idiopathic GHD-related anemia given rhGH and the GH/IGF-1 axis's role in bone-marrow red-cell production. The individual abstract page returned no retrievable content on repeated attempts during this review, so exact sample size, hemoglobin change magnitude, and statistical significance are not confirmed and are not asserted here.

Mechanism

Named: GH/IGF-1 stimulates erythropoiesis, directly and via erythropoietin; GHD is an established (often mild/subclinical) cause of normocytic anemia generally reported to improve with GH replacement.

Counter-evidence held on record

None found in the opposite direction. Reverse-direction (potentially corrective), not a depletion of oxygen-carrying capacity. Magnitude is unconfirmed here due to a genuine access limitation (see Sources) and should be re-verified before any stronger claim is published.

Limits on what this shows

• Key negative/null findings: This entire entry is the null finding.
• At-risk subgroups: None identified.

Regulatory status

Not addressed in the FDA label.

Population evidence

Sinha et al. (2014), PMID 23711232 (same study as the Mitochondrial burden entry — see Overlap map). PCr recovery half-time, a direct kinetic marker of mitochondrial ATP resynthesis capacity, did not differ significantly between 23 GH-treated GHD adults, 22 untreated GHD adults, and 20 healthy controls (P=0.53).

Mechanism

None established; this entry documents an explicitly tested and negative finding in the target drug's own treated population.

Counter-evidence held on record

No study found in the opposite direction (i.e., no evidence of somatropin-impaired ATP production). Presented as reassuring context from a single cross-sectional study, not a guarantee. Does not replace individualized clinical monitoring for fatigue in treated patients, which the same research group attributed to central rather than peripheral/metabolic causes.