Final answer:
Specific gravity is a measure of the density of urine compared to pure water; the presence of proteins and glucose can falsely elevate it. The corrected specific gravity accounts for these solutes, and is calculated by subtracting certain values for each gram per liter of protein and glucose from the measured specific gravity.
Step-by-step explanation:
The subject of this question revolves around the measurement and interpretation of urine specific gravity in a diabetic patient with oliguria. Specific gravity is a measure of the density of urine compared to pure water, and an increased specific gravity can indicate the presence of excess solutes such as proteins and glucose in the urine. The typical specific gravity of urine is between 1.005 and 1.030. However, when significant quantities of proteins or glucose are present, the specific gravity may be falsely elevated. Since this patient's urine has a 3+ protein and a 3+ glucose, the measured specific gravity of 1.042 needs to be corrected. To find the corrected specific gravity, you subtract 0.003 for each gram of protein and 0.004 for each gram of glucose from the measured specific gravity. Assuming that 3+ corresponds to roughly 30 g/L for protein and glucose, the corrected specific gravity is: 1.042 - (0.003 × 3) - (0.004 × 3) = 1.042 - 0.009 - 0.012 = 1.021. However, this is not one of the options provided, which suggests that the specifics of the correction formula may differ from what is assumed here.