Total CK
Typically >1000
Correlates with degree of rigidity
CBC
WBC >10K is typical
Chemistry
May show hypocalcemia, hypomagnesemia, hyperkalemia, metabolic acidosis
Urinalysis
Myoglobinuria (from rhabdo)
LFTs
Transaminitis
CT/LP
CSF may have mildly elevated protein
Typically >1000
Correlates with degree of rigidity
WBC >10K is typical
May show hypocalcemia, hypomagnesemia, hyperkalemia, metabolic acidosis
Myoglobinuria (from rhabdo)
Transaminitis
CSF may have mildly elevated protein
History of a new serotonergic drug or a dose increase of a serotonergic drug are helpful
Serotonin syndrome is usually much more acute in onset than<unk>  which may develop over days or weeks
Presence of ‘lead pipe’ rigidity is typical of<unk> , while serotonin syndrome typically manifests with tremor and hyperreflexia
Elevations in CK, LFTs, and WBC, coupled with a low iron level, distinguishes<unk>  from serotonin syndrome among patients taking both<unk>  and serotonin agonist medications simultaneously
Neuroleptic malignant syndrome
Serotonin Syndrome
Limbic encephalitis
Serotonin syndrome more likely to have hyperreflexia, myoclonus, ataxia, nausea and vomiting, diarrhea
Osmotic demyelination syndrome
Rigidity and hyperthermia, if present, is less severe than in NMS; more commonly presents with clonus and hyperreflexia
Posterior reversible encephalopathy syndrome
Malignant Hyperthermia