Diagnostics should be directed based on symptoms.  Non-carbonyl<unk>  exposures are typically benign and limited to skin complaints; these may require no further work up.<unk>  carbonyl exposures require more intensive evaluations including but not limited to:
Arterial blood gas analysis, CXR in the setting of shortness of breath
EKG
Liver enzymes
Serum electrolytes, including serum creatinine
Non-contrast CT head in the setting of significant neurological findings to rule out cerebral edema
May be obtained from the urine, blood, and serum
Always collect in metal-free, acid-washed container
Average serum [Ni] = 0.3 mcg/L
Urine<unk>  concentrations are preferentially obtained over 8 hours
upper limit of normal = 5 mcg/L
< 100 mcg/L = mild<unk> 
100 -  500 mcg/L = moderate toxicity
> 500 mcg/L = severe poisoning
Nickel toxicity
Nickel carbonyl exposures should be considered in all relevant occupational or industrial exposures presenting with significant pulmonary, cardiac, or neurological findings. Other occupational and toxicological exposures that should be considered.
Zinc toxicity
Manganese
Mercury toxicity
Cadmium
Gold toxicity
Elemental mercury