Question Title: Blood work

Some time ago, I complained about my weak legs and had difficulty climbing the stairs. He ordered 8 different blood tests (TSH, ANA, CK, complement, C3 and C4, cryoglobulins, etc) to rule out or identify what was causing my problem. I understood what each test meant for except for two: lactate and albumin. The lactate was elevated, and albumun was decreased. For the last two years, my albumin levels seem to be low or marginal? What I want to know is why the neurologist wanted to know about lactate and albumin. What are their roles with the weak legs? Any significance of those results? Through the tests, I was diagnosed as hyperthryoid. I hope I make sense. Many thanks in advance.

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Lactate is usually used for exploring metabolic problems such as mitochondrial disease. Mitochondria are the "engines" in each cell in your body which make "energy molecules" such as ATP. It's a lot more complicated than that, but there are certain (very rare) disorders which involve weakness of muscles and abnormal (usually elevated) lactate can help detect them.

I'm not sure what albumin is for. I've always used it as a measure of general nutritional status, sometimes it is abnormal in liver and kidney diseases. Any more than that and I'd be in over my head, since I just don't use the test much these days.

A neurologist evaluating weakness will take a very orderly approach: using the history (details provided by you at interview) and the exam, the first task is to localize the problem. Is the weakness coming from the brain, spinal cord, nerve roots, nerves, nerve-muscle junction, or muscle? If that question is not answered, it is hard to interpret any other tests designed to reveal the pathologic process underlying the symptoms. You may ask your doctor the specific question he/she was asking for each lab test. Sometimes it's a fishing expedition (I do that too) and sometimes there are very specific hypotheses that are being tested with each blood test.

I hope this helps. As you know, this information is provided for your general educational benefit only. Any specific comment regarding diagnosis, treatment, and prognosis must come from your doctor after appropriate evaluation. CCF MD mdf.