AM Report 04/11/17 Hypothyroid Myopathy

Myopathy is not only due to trauma, crush injury or statins! 

Etiologies of non-traumatic-non-exertional rhabdomyolysis (elevated CK)

ALCOHOL, illicit drugs- from A (methAmphetamine) to Z (ecstasy), all are associated with rhabdo
Medical drugs, commonly statins/fibrates but MANY implicated drugs (see below
-Infectious (including HIV!)
-Seizures, DTs, or restraints (avoid prolonged restraints of this reason and re-assess need for them frequently
Hypothyroidism (more on this later)-Check that TSH!
-NMS, Malignant Hyperthermia
Inflammatory myopathies(Dermatomyositis/Polymyositis/Dermatomyositis)
Electrolyte abnormalities (eg: HypoK, HypoPhos)

List of implicated drugs (not a comprehensive list)


Make sure you do a comprehensive history when evaluating for rhabdo and consider secondary causes per above, including meds and thyroid abnormalities

What are some manifestations of SEVERE hypothyroidism (Myxedema Coma)

-See our other blog post for more details but the THREE cardinal features of Myxedema Coma are ALTERED MENTAL STATUS (not commonly Coma as the name states), HYPOthermia, and a PRECIPITATING EVENT (commonly an infection, or cold exposure, or MI or trauma)
-The “classic” patient who gets Myxedema Coma is an elderly female >60 years with history of untreated hypothyroidism presenting during the winter months. However, classic is not always so classic.
-Other findings include Bradycardia, HYPOnatremia, HYPOglycemia, and HYPOtension

Treatment of Myxedema Coma

IV Levothyroxine (L4, sometimes L3 but controversial) along with stress dose steroids unless adrenal insufficiency is ruled out (get that AM cortisol!). Otherwise you can precipitate an ADRENAL CRISIS

What does hypothyroid myopathy look like? 

-Elevation in CK usually less than 10x ULN (seen in 60-90 % of patients), usually triggered by intense exercise or concurrent statin therapy (like our patient)
Muscle hypertrophy (thickened doughy appearance of skin and subQ tissues)
Proximal myopathy (progressive symmetric proximal weakness- can look like an inflammatory myopathy!)

Treatment

-Treat the hypothyroidism and symptoms usually improve

Take home point

-Did I mention that hypothyroidism is a common etiology of rhabdomyolysis?

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