here's how all that links to zinc. besides being known to be low in ms patients, zinc does seem to be a lowest common denominator for a lot of things with suspected connections to ms.
Effect of Zinc Supplementation on Incidence of Infections and Hospital Admissions in Sickle Cell Disease (SCD)http://idpas.org/pdf/2687EffectOfZinc.pdf
"Mycoplasma and Chlamydia pneumoniae
cause the most common infections associated with the acute chest syndrome  in SCD patients. ... Zinc supplementation in zinc deficient subjects (Grs A and B), resulted in an increase in zinc concentration in the plasma and cells, an increase in IL-2 production, and a decrease in the incidence of infections."
(and by the way, sickle cell disease is a protein folding disease, and proper protein folding relies on zinc in its structural role)
Zinc status and serum testosterone levels of healthy adults.http://www.ncbi.nlm.nih.gov/pubmed/8875519
"Zinc supplementation of marginally zinc-deficient normal elderly men for six months resulted in an increase in serum testosterone [an androgen]
from 8.3 +/- 6.3 to 16.0 +/- 4.4 nmol/L (p = 0.02)."
Topical treatment of recurrent herpes simplex and post-herpetic erythema multiforme with low concentrations of zinc sulphate solutionhttp://onlinelibrary.wiley.com/doi/10.1 ... x/abstract
"The preventive effect of low concentrations of zinc sulphate solution in recurrent herpes simplex of the skin and oral mucous membrane
Topical application of zinc-solutions: a new treatment for herpes simplex infections of the skin?http://www.ncbi.nlm.nih.gov/pubmed/6155033
"Eighteen patients experiencing 22 episodes of recurrent herpes simplex skin infections
were treated with topical applications of a solution containing 4% zinc sulphate in water. In all patients, pain, tingling and burning stopped completely within the first 24 hours of zinc therapy. Crusting occurred within 1-3 days and no adverse effects were observed."
Effect of Zinc Supplementation on Markers of Insulin Resistance, Oxidative Stress, and Inflammation among Prepubescent Children with Metabolic Syndrome http://www.ncbi.nlm.nih.gov/pubmed/21028969
"In [both] groups, hs-CRP and markers of insulin resistance
decreased significantly after receiving zinc, but increased after receiving placebo."
Effect of Zinc Supplementation on Serum Homocysteine in Type 2 Diabetic Patients with Microalbuminuriahttp://www.soc-bdr.org/rds/archive/6/1_ ... ex_en.html
"Zinc supplementation reduced serum homocysteine
and increased vitamin B12 and folate concentrations in type 2 diabetic patients with microalbuminuria."
Oral zinc therapy normalizes serum uric acid level
in Wilson's disease patientshttp://www.ncbi.nlm.nih.gov/pubmed/3777013
"Although s-UrA levels were low before oral zinc therapy (mean +/- SD, 1.60 +/- 0.20), they increased (mean +/- SD, 2.63 +/- 0.32) to within normal range (2.8-8.0 mg/dl) after therapy."
Zinc Deficiency-induced Iron Accumulation
, a Consequence of Alterations in Iron Regulatory Protein-binding Activity, Iron Transporters, and Iron Storage Proteins (in vitro)http://www.jbc.org/content/283/8/5168.abstract
i'd say, if you want to keep it to one test, go for serum zinc.