A manual hemoglobin is determined on a patient, and the dilution still appears turbid after letting it sit for 15 minutes. The stained blood film is examined, and sickle cells are observed on the blood film

Equal volumes of the diluted hemoglobin sample and water are mixed together, and the absorbance of this read on a spectrophotometer. How should the hemoglobin result be determined from the standard calibrated graph?

a. Add the results from the turbid and second dilution together and divide by 2.
b. Multiply the result obtained from the graph on the diluted specimen by 2.
c. Divide the result obtained from the graph on the diluted specimen by 2.
d. There was no reason to perform this second dilution.

ANS: B
Red cells that contain Hb S (sickle hemoglobin) are resistant to lysis in some cyanmethemoglobin reagents. When this occurs, the cyanmethemoglobin dilution should be mixed with an equal part of water, and the optical density (percent transmission) read. This optical density reading is read from the calibration graph to obtain the hemoglobin result. However, because the diluted specimen was diluted 1:2 by water, this result must be multiplied by 2 to obtain the patient's result.