Genryzon Treatment Discontinuation

Genryzon Treatment Discontinuation

Decide whether the child is at the end of their growth-response window and should stop weekly somatrogon. Under-treating and over-treating are both real risks.

Step 1 — Apply the three physiological stopping gates

Stop somatrogon if ANY ONE of the following is met (the monograph is explicit):

Any one gate met → discontinue Genryzon.

Practical workflow:

• At every 6–12 month review, calculate height velocity from the last two measurements (properly stadiometer-measured, same time of day)
• Annually update bone age
• If HV <2 cm/yr and the child is at or approaching pubertal completion → confirm with a repeat height in 3 months (measurement error can transiently look like a stall)
• If HV <2 cm/yr sustained across two visits**, or **bone age >14 (girls) / >16 (boys), or epiphyses closed → stop

Step 2 — Confirm before stopping

Before pulling the trigger, exclude reversible causes of a false stall:

• Measurement technique — was the stadiometer used, shoes off, same posture?
• Adherence — has the child been giving the injections properly? (technique check, count remaining pens)
• IGF-1 SDS below target on a day-4-post-dose sample → could be under-dosed; check genryzon-igf1-titration first
• Untreated hypothyroidism or increased glucocorticoid dose — either blunts growth response
• New puberty issue — hypogonadism suppressing pubertal growth spurt
• Nutrition / chronic illness / malabsorption — child sick since last visit?
• Concurrent oral estrogen (girls) — ↓ IGF-1 response; adjust dose per genryzon-igf1-titration

Only after those are excluded is a genuine growth stall confirmed.

Step 3 — Safety-driven stops (independent of Step 1)

Stop Genryzon immediately — regardless of growth status — if any of:

• Confirmed active tumour (new malignancy OR recurrence)
• Confirmed second neoplasm in a childhood cancer survivor on GH
• Severe systemic hypersensitivity reaction (anaphylaxis, angioedema) → do not rechallenge; switch to a somatrogon-free product only after specialist review
• Acute critical illness — post open-heart or abdominal surgery, multiple trauma, acute respiratory failure (contraindication; hold at least during acute phase)
• Any evidence of tumour growth or malignancy signal while on GH

Step 4 — Consider transition to adult GHD assessment (do NOT auto-continue)

After paediatric discontinuation, do not automatically continue GH into adult life. Instead:

• After stopping paediatric therapy, retest for GHD in adulthood with adult provocative testing (per local adult endocrine protocol — ITT, glucagon test, or macimorelin)
• Adult GHD is a separate indication with different drugs, doses, and clinical justification (metabolic + quality-of-life, not growth)
• Transition-age gap (typically 6–12 months) between stopping paediatric GH and retesting is standard
• Refer to adult endocrinology for the transition assessment

Step 5 — Communicate the stop to family

Explain the decision clearly:

• Why now: growth potential is nearly exhausted; continuing has no benefit and adds side-effect risk without meaningful height gain
• What to expect: IGF-1 falls back to pre-treatment levels within weeks; no rebound growth loss; no withdrawal effects
• Adult transition: the child may need a formal adult GHD reassessment in 6–12 months — arrange the referral now
• Ongoing monitoring: the child still needs endocrine follow-up for other pituitary axes (thyroid, adrenal, gonadal) if there was structural pituitary pathology
• Batch record: document the stop date, the reason (which gate was met), and the last IGF-1 and auxological measurements

Guardrails

• The three gates are OR gates, not AND — one gate met is sufficient to stop. Do not wait for all three
• A single measurement of height velocity <2 cm/yr is not enough — confirm with a second measurement 3 months later, and exclude reversible confounders (Step 2) before stopping
• Bone age is the strongest predictor of remaining growth potential — a chronological age of 17 in a boy with bone age of 13 is very different from a chronological age of 17 with bone age of 16
• Never continue Genryzon "just because insurance covers it" — the monograph is explicit; continuing beyond these gates is off-label and adds risk (glucose intolerance, oedema, arthralgia, IH, malignancy signal) with no growth benefit
• Never assume paediatric GHD = adult GHD — a substantial fraction of children with isolated idiopathic GHD have a normal adult GH axis on retesting. Retest before restarting in adulthood
• A tumour signal is an absolute immediate stop — do not wait for the next planned visit
• Bone age >14 (girls) / >16 (boys) is the monograph's cutoff — some centres allow slightly higher bone ages in specific catch-up scenarios, but that is an off-monograph judgement call and should be documented explicitly
• Do not stop somatrogon at the same visit as making the diagnosis of a co-morbidity unless it's a safety-driven stop (Step 3). Stabilise the co-morbidity first, then re-evaluate growth response

Related MD2SKILL skills

• genryzon-prescribing-guide — starting and maintaining Genryzon
• genryzon-igf1-titration — rule out under-dosing before calling a stall genuine
• genryzon-red-flag-monitoring — the safety-driven stops overlap with this skill
• genryzon-pretreatment-screening — the mirror image (before first dose)

Source

Pfizer Products India Pvt. Ltd. GENRYZON® (Somatrogon) Solution for Injection in Pre-filled Pen — Prescribing Information (India). LPD version 2022-0081166 (PfLEET 2022-0081166). Section 4.2 "Treatment evaluation and discontinuation" and Section 4.3 "Contraindications".