Myotonic dystrophy (Steinert's disease)
BioMG follows French guidelines. Adapt it to the guidelines and the tests available where you practise.
Diagnosis
- Geneticist's opinion: diagnostic confirmation relies on molecular analysis, performed after informing the patient and/or their parents/legal guardian about the disease being sought, the means of detecting it, the degree of reliability of the tests, the possibilities of prevention and treatment, and the risks of genetic transmission of the disease.
Laboratory tests
- Testing for the Steinert mutation
Initial tests: look for endocrine involvement
Laboratory tests
- Fasting plasma glucose
- HbA1c
- Lipid profile
- AST
- ALT
- GGT
- ALP
- Serum testosterone + SHBG
- Serum calcium
- Serum albumin
- Serum phosphate
- 25-hydroxyvitamin D
- Bilirubin (total and conjugated) (if AST, ALT or GGT raised)if needednon-French guidelineThe international consensus of the Myotonic Dystrophy Foundation has liver enzymes and bilirubin measured at the initial tests then every year; chronic elevation of enzymes is usual and does not require a biopsy [3,4].
- PTH
- TSH (+ free T4 and free T3 as reflex tests)
- CK (baseline value, before anaesthesia)if neededBefore anaesthesia: a preoperative CK measurement may be useful for information (baseline value) [1].
- FBCif neededHypogonadal man treated with testosterone: monitoring of PSA and blood count to look for polycythaemia [1].
- PSAif neededHypogonadal man treated with testosterone: monitoring of PSA and blood count to look for polycythaemia [1].
Also consider
Do not order
- Laboratory screening for adrenal involvement in the absence of symptoms: "No screening recommended in the absence of symptoms" (PNDS) [1].
Annual follow-up of the asymptomatic adult (schedule of the French national care protocol)
Laboratory tests (once a year)
- Fasting plasma glucose
- HbA1c
- Lipid profile
- AST
- ALT
- GGT
- ALP
- Serum calcium
- Serum albumin
- Serum phosphate
- 25-hydroxyvitamin D
- Serum testosterone + SHBG (adult man)if neededAdult man only: monitor serum testosterone and SHBG [1].
Every 5 years (if normal)
- TSH (+ free T4 as a reflex test)
Sources (5)
- Centre de référence des maladies neuromusculaires (CHU de Lille), filière FILNEMUS. Protocole national de diagnostic et de soins (PNDS) : dystrophie myotonique de type 1 (« maladie de Steinert »). Texte du PNDS, octobre 2024 (HAS, publié décembre 2024).
- Assurance maladie. Nomenclature des actes de biologie médicale (NABM), version 105 : actes 4082 (génétique moléculaire, autres affections), 1139 (25-OH vitamine D), 0983 (PTH), 1577 (HbA1c).
- Myotonic Dystrophy Foundation. Consensus-based Care Recommendations for Adults with Myotonic Dystrophy Type 1, version longue (janvier 2021), chapitres « Endocrine and metabolic » et « Diagnosis ».
- Ashizawa T, Gagnon C, Groh WJ, et al. Consensus-based care recommendations for adults with myotonic dystrophy type 1. Neurol Clin Pract. 2018;8(6):507-520.
- Johnson NE, Aldana EZ, Angeard N, et al. Consensus-based care recommendations for congenital and childhood-onset myotonic dystrophy type 1. Neurol Clin Pract. 2019;9(5):443-454.