Are there variances of calculated free testosterone attributed to variations in albumin and sex hormone-binding globulin concentrations in men?

OBJECTIVE: Calculated free testosterone (cFT) is determined from total testosterone (TT), sex hormone binding globulin (SHBG), and albumin (Alb) levels using mathematical formulae. Variations in cFT due to changes in SHBG or Alb have not been investigated. We evaluated potential cFT variances determined with fixed Alb (4.3 g/dL) and measured Alb, and the point at which low SHBG and Alb combinations produced significant cFT variance. METHOD: We analyzed 11,176 data points from 5,797 men. cFT values with fixed versus actual Alb values were evaluated and compared. cFT levels were theoretically determined for all possible combinations of TT, SHBG, and Alb (8,343,552 combinations). Agreement between the 2 measures was assessed with Lin's concordance coefficient. RESULTS: Mean Alb was 4.06 ± 0.32 g/dL. Mean SHBG was 39.0 ± 23.6 nmol/L. A fixed Alb of 4.3 g/dL did not produce significant variance for most cFT evaluations. Accuracy decreased when Alb was ≤3.5 g/dL in combination with SHBG ≤30 nmol/L, and this occurred in 1.2% of all data points. CONCLUSION: A fixed Alb of 4.3 g/dL is acceptable for most clinical evaluations. If Alb is ≤3.5 g/dL and SHBG is ≤30 nmol/L, the variance increases, and a free testosterone (FT) measurement by equilibrium dialysis is warranted for better accuracy.

Dengue fever mimicking plasma cell leukemia.

Extreme plasmacytosis in peripheral blood is a rare finding most often associated with plasma cell leukemia but rarely with other malignancies, infectious diseases, or drug reactions. We report the case of a 40-year-old man who was a US expatriate working and traveling in East Asia. He presented with complaints of fever, myalgia, headache, vomiting, and diarrhea of 3 days' duration. An initial evaluation revealed elevated liver function tests, thrombocytopenia (68 x 10(3)/microL), and a white blood cell count of 5.8 x 10(3)/microL with 19% plasma cells (1100/microL), 9% abnormal plasmacytoid lymphocytes (520/microL), 37% polymorphonuclear leukocytes, 3% band forms, 27% lymphocytes, 4% monocytes, and 1% eosinophils. An extensive evaluation was performed, including infectious disease serologies, a bone marrow biopsy, and flow cytometry. During the course of 3 days, his symptoms and hematologic findings improved dramatically. Serologic results were reactive for dengue (immunoglobulin M [IgM] positive, reciprocal IgG titer, 655 360), consistent with a secondary infection of unknown serotype. He remains well 4 years later. To our knowledge, plasmacytosis to this degree has not been described in dengue fever, but atypical lymphocytosis is common. In patients from dengue-endemic areas, even extreme plasmacytosis should be assessed to determine whether it is transient and related to an acute illness before proceeding to an extensive evaluation.