Can metobolic disease cause fasciculations. have high cpk 744 high adolese and low t. rheumatologist thinks metobolic. clean emg/ns. worried als. 36?

It can: Autoimmune diseases and Neurological disease are more likely; for which you have had good attention and thorough work up by your Rheumatologist, I believe. Electrolyte imbalance with Potassium, Mg, Calcium imbalance, Problem with Glucose( glycemic control) and Thyroid/Parathyroid dysfunctions are other Metabolic causes of Fasciculations

Possibly..: The differential diagnosis of ALS is quite extensive, probably too much to post here. EMG often shows both acute and chronic denervation in ALS although conventional MRI is usually normal in ALS. You could pursue a lumbar puncture and/or muscle biopsy for the possibility of some more definitive answers.