Genryzon Pretreatment Screening

Genryzon Pretreatment Screening

Complete this checklist BEFORE the first Genryzon dose in a child with confirmed paediatric GHD. Missing any of these leads to preventable harm.

Step 1 — Reconfirm the diagnosis of GHD

Genryzon is indicated only for growth disturbance due to insufficient GH secretion. Before starting, verify:

• Two provocative GH stimulation tests consistent with GHD (or one test + supportive auxology + low IGF-1/IGFBP-3 SDS + MRI evidence, per local guideline)
• Auxology consistent with GHD: height SDS <−2, or height SDS <−1.5 with poor growth velocity, or drop in height percentile
• MRI pituitary to identify structural cause (idiopathic vs organic; excludes intracranial tumour — see Step 5)
• Bone age — for growth-potential assessment and later discontinuation planning

Do NOT start in constitutional delay of growth and puberty (CDGP), familial short stature, or other non-GHD causes of short stature — Genryzon is not indicated and does not improve final height in these conditions.

Step 2 — Thyroid function

Order: TSH + free T4.

Why: hypothyroidism blunts the response to growth hormone. Somatrogon can also unmask previously undiagnosed central hypothyroidism (GH increases T4→T3 conversion).

Action:

• Pre-existing hypothyroidism → treat first. Do not start Genryzon until euthyroid on levothyroxine
• Normal at baseline → recheck TFTs at each 6–12 month review
• Consider central hypothyroidism in any child with a hypothalamic/pituitary pathology on MRI — treat empirically per specialist judgement even if TSH looks "normal"

Step 3 — Adrenal function

Why: GH may unmask central (secondary) hypoadrenalism. Starting somatrogon in an unrecognised ACTH-deficient child risks adrenal crisis under stress. Additionally, GH decreases cortisone→cortisol conversion, so children already on glucocorticoid replacement may need dose escalation once GH is started.

Order:

• Morning cortisol (8 AM) — the entry-level test
• If borderline or clinical suspicion → ACTH stimulation test or ITT per local protocol
• If organic pituitary lesion / multiple pituitary hormone deficiency → assume central hypoadrenalism and start hydrocortisone replacement empirically

Action:

• Any evidence of central hypoadrenalism → start hydrocortisone replacement BEFORE Genryzon, and warn family about stress dosing / sick-day rules
• Already on glucocorticoid replacement → plan to review dose at 4–8 weeks after starting Genryzon; often needs dose ↑
• Normal adrenal axis at baseline → still monitor for symptoms of adrenal insufficiency (fatigue, hypotension, hypoglycaemia) at each visit

Step 4 — Glucose tolerance

Why: GH reduces insulin sensitivity and can precipitate hyperglycaemia. Higher-risk children (family history of T2DM, obesity, high-risk ethnicity, previous glucocorticoid exposure, syndromic obesity) must be flagged.

Order:

• Fasting plasma glucose + HbA1c as baseline
• OGTT if any risk factor or borderline FPG/HbA1c

Action:

• Normal at baseline → repeat FPG/HbA1c annually (more often if risk factors)
• Impaired fasting glucose / IGT / overt diabetes → involve paediatric diabetologist; if starting Genryzon anyway, plan more frequent glucose monitoring and be prepared to adjust insulin/OAD doses upwards once GH is on board

Step 5 — Tumour clearance

Why: somatrogon is contraindicated in active malignancy. Children with prior CNS pathology require specific clearance.

Verify:

• Any prior intracranial tumour must be inactive — imaging within the recommended surveillance interval
• Antitumour therapy (surgery, radiation, chemotherapy) must be completed before starting GH
• Childhood cancer survivors — flag for elevated risk of second neoplasm on GH (especially meningioma after cranial radiation); document baseline surveillance plan
• No active malignancy anywhere — check most recent oncology/imaging summary

Action:

• Any suggestion of tumour activity → do not start. Loop oncology in for clearance
• Cleared for GH → document the clearance in the notes with date and imaging reference

Step 6 — Baseline fundoscopy

Why: benign intracranial hypertension (IH) with papilloedema, headache, vision changes, nausea/vomiting is a recognised somatrogon adverse event. A baseline fundus exam provides a comparator if IH is later suspected.

Order: fundoscopy — by ophthalmology if available, or by trained clinician

Action:

• Baseline documented → refer to comparator if any later ocular / neurological symptoms
• Baseline abnormal (papilloedema, unexplained disc changes) → do NOT start Genryzon; investigate the underlying cause

Step 7 — Rule out Prader-Willi syndrome (or confirm it's PWS + GHD)

Why: somatrogon has not been studied in PWS. Sudden death has been reported in PWS children on GH who have severe obesity, upper airway obstruction, sleep apnoea, or unidentified respiratory infection. Genryzon is not indicated for PWS-related growth failure unless the child also has confirmed GHD.

Action:

• Suspected PWS features (neonatal hypotonia, hyperphagia, hypogonadism, characteristic facies, obesity) → do not start until PWS is excluded by methylation testing / SNRPN analysis
• Confirmed PWS without confirmed GHD → Genryzon not indicated. Refer to PWS specialist
• Confirmed PWS WITH confirmed GHD → treatment may proceed but with:
  • Formal sleep study to exclude/quantify sleep apnoea before starting
  • ENT review if any upper airway concern
  • Weight-management plan and family counselling about respiratory risk
  • Never start during an intercurrent respiratory infection

Step 8 — Baseline auxology and family readiness

Document at baseline:

• Standing height, weight, BMI, height SDS, weight SDS, mid-parental height SDS
• Growth velocity from prior visits (cm/year)
• Bone age (X-ray of left hand)
• Tanner stage
• Pubertal onset timing (age at breast bud / testicular volume 4 mL)

Confirm family is ready:

• Understand the diagnosis and expected duration of therapy
• Can commit to a weekly injection routine (any day of week, any time of day, but same day each week)
• Trained in pen technique, injection sites (abdomen / thighs / buttocks / upper arms), rotation, and disposal
• Caregiver assigned for injections into upper arms or buttocks (child cannot self-inject those sites)
• Knows what to do if a dose is missed (see the missed-dose rule) and what red-flag symptoms to escalate

Guardrails

• Do not compress this checklist to "just check TFTs". Adrenal, glucose, ocular, tumour, and PWS steps each block a specific harm
• Central hypoadrenalism can be occult — a normal random cortisol does not exclude it. If any hypothalamic / pituitary structural lesion is present, err on the side of starting hydrocortisone replacement before GH and confirming with formal testing later
• A single normal FPG does not exclude glucose intolerance — repeat at follow-up, and use HbA1c / OGTT in high-risk children
• Baseline fundoscopy avoids the diagnostic dilemma of "was that papilloedema present before we started?" if IH is later suspected
• Do NOT start during any acute intercurrent illness — acute critical illness (post open-heart / abdominal surgery, multiple trauma, acute respiratory failure) is an absolute contraindication
• Never start Genryzon in a child with active malignancy — pause GH pending oncology clearance
• In female adolescents post-menarche, consider whether OCP / other oral estrogen therapy is likely to be started — this influences later IGF-1 titration (see genryzon-igf1-titration)
• Document everything — batch number of the first pen, all baseline values, all clearance letters. Growth hormone therapy is often audited

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). Sections 4.3 "Contraindications" and 4.4 "Special Warnings and Precautions for Use".