To the Editor:—
A accolade is due Dr. Sumner Marshall for his communication, "Urinary Specific Gravity During Excretory Urography," appearing in the Feb 1, 1964, issue of The Journal (187:333). We can endorse his interpretation of the value of the specific gravity of the urine specimen obtained before and after intravenous urography. Our experience with excretory urography carried out as an office procedure demonstrated that approximately 86% of patients had initial urinary specific gravities of 1.018 or higher. Calibrated hydrometers were used, and corrections were made for protein and sugar, but not for temperature, since the measurements were made immediately at 37 C. Invariably, this group had excellent renal function when verified. Thus, the advantage accrued is the elimination of 86% of patients from further extensive procedures. The physician is thereby able to concentrate his attention on a limited number of patients, ensuring more careful timing, collections, and procedures,