Volume 10, Number 04

LYME DISEASE What tests to order from the lab Lyme disease follows a tick bite that infects the host with a spirochete called Borrelia burgdorferi. In the United States, the northeast, upper midwest, and parts of the west have been identified as geographic foci for the disease. In Ontario, the Long Point area has been identified. However there are reports from other locations that suggests that the disease is spreading. Most cases occur in the summer months and affect visitors and residents alike. There are three clinical stages involved in this disease but overlap may occur and some patients may not show all stages. The hall-mark of the disease is erythema migrans that begins as a small red macule or papule at the site of the tick bite. Within a few days to a month, this lesion enlarges and often assumes a "bull's-eye" appearance. 86% of patients have this lesion. There is only one useful lab test for the disease and it is a test of the serum for the presence of antibodies against the causative agent, B. burgdorferi. The presence of these antibodies varies with the stage of the disease and the relationship is shown in the following table. Findings in Lyme Disease Stage Duration Findings Serology 1 4 weeks Erythema migrans Influenza-like illness Severe fatigue Musculoskeletal pains Headache Stiff neck + or - 2 days to months CNS disease with meningitis, encephalitis, Bell's palsy Peripheral involvement with radiculopathy, neuropathy Cardiac with heart block, myopericarditis, CHF Ophthalmitis + 3 months to years Asymmetric arthritis Severe, chronic CNS disease + Most cases of Stage 1 disease are based on clinical findings since about half will be serologically negative. However almost all the cases of Stage 2 and 3 are positive. Only one specimen is needed and consists of enough blood to yield 1.0 ml. of serum. Results are expressed as a decimal fraction (>0.40=positive).

BLOOD CHEMISTRY RESULTS Are there seasonal variations? Significant variation in routinely measured biochemical tests occurring over the course of the seasons would have definite implications to diagnostic decisions. Only a few studies have been made to determine if such variations occur and these studies indicate that such may be the case. Unfortunately, however, many of these studies were not done according to the current-state-of-the-art. In a more recent study1 with well-controlled instrumentation (SMAC system), and standardized blood collection procedures, the following parameters were followed over a four year period in a large healthy population in the 30-39 year age group: Glucose Urea Nitrogen Creatinine Uric acid Calcium Inorganic phosphorus Total protein Albumin Total bilirubin Cholesterol Triglyceride Alkaline phosphatase AST ALT LDH GGT CK Serum iron The authors found many statistically highly significant differences between the seasons, but only in the cases of uric acid and triglycerides was the percentage of differences between the highest and lowest seasonal mean greater than the inter-assay Coefficient of Variation of the methods. To summarize the findings: Uric Acid was higher in the summer by 5% compared with the fall in women, and by 7% in the case of Men. Triglyceride was 6% higher in the spring compared with the fall in women while it was an amazing 22% higher in winter compared with the fall in men. 1. Letellier et al. Clin. Biochem. 15 (4) 206-211 (1982)

ANEMIAS A Guide to Diagnosis Anemia is probably the most common hematologic problem encountered, and its prevalence increases in both men and women with each decade. Anemia, however, is not a diagnosis in itself, but rather a laboratory finding that suggests an underlying disease. Sometimes the cause is not readily evident and it is the purpose of this guide to help the clinician follow-through in an orderly fashion to find it. Despite its frequency, anemia is sometimes hard to define since "normal" values for different age groups and for different populations have been controversial. Although some use as criteria a hemoglobin level below 155 g/L for men and 136 for women, the World Health Organization uses 130 g/L for men and 120 g/L for women. The prevailing opinion is that anemia is not a normal manifestation of aging and an appropriate cut-off in elderly patients may be 120 g/L. Clinical judgment regarding evaluation is important.

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