Specific gravity of urine

Fig. 15. Maximum specific gravity of urine in cases of parathyroid tumor before and after parathyroidectomy (calculated from data of Hellstrom, 1958). Reproduced by permission of Postgraduate Medicine.

Many of these tests must be performed by using sophisticated and sensitive instrumentation. However, a very simple test, the measurement of the specific gravity of urine, can be an indicator of diabetes mellitus or Bright s disease. The normal range for human urine specific gravity is 1.010-1.030. 

A hydrometer, a weighted glass bulb inserted in a liquid, may be used to determine specific gravity. The higher it floats in the liquid, the more dense the liquid. A hydrometer that is calibrated to indicate the specific gravity of urine is called a urinometer. 

A hydrometer, used in the measurement of the specific gravity of urine. 

Measure the specific gravity of urine specimen. Determine if kidneys are clearing waste materials. 

FIGURE 2.12 A hydrometer is used to measure the specific gravity of urine, which, for adults, is 1.002-1.030. 

Specific gravity is one of the few unitless values you will encounter in chemistry. An instrument called a hydrometer is often used to measure the specific gravity of fluids such as battery fluid or a sample of urine. In Figure 2.12, a hydrometer is used to measure the specific gravity of urine. 

On occasion, a patient may need to self-administer vasopressin by the parenteral route. If so, the nurse instructs the patient or a family member in the preparation and administration of the drug and measurement of the specific gravity of the urine. 

The specific gravity of normal urine may range from 1.008 to 1.030. After excessive fluid intake (like a beer party), the specific gravity may be on the low side after heavy exercise and perspiration, it may be on the high side. High specific gravity indicates excessive dissolved solutes in the urine. 

The specific gravity of your urine samples will be measured with the aid of a hydrometer (urinometer see Fig. 52.1). Place the bulb in a cylinder. Add sufficient urine to the cylinder to make the bulb float. Read the specific gravity of the sample from the stem of the hydrometer where the meniscus of the urine intersects the calibration lines. Be sure the hydrometer is freely floating and does not touch the walls of the cylinder. In order to use as little urine as possible, the instructor may read the normal and two pathological urine samples for the whole class. If so, you will measure the specific gravity of your own urine sample only. 

Comparisons of exposed populations to controls have shown a variety of changes in exposed workers, ranging from no effects (Bernard et al. 1987 Piikivi and Ruokonen 1989) to increases in urinary protein (Stewart et al. 1977), the specific gravity of the urine (Ehrenberg et al. 1991), and urinary TV-acetyl-... 

Einbrodt et al. (1976) exposed students to 0.26-0.92 ppm formaldehyde vapors for 3 hours, with urine samples collected immediately after exposure and 21 hours after exposure. Urine formaldehyde and urine formic acid (formate) concentrations were found to be higher immediately after exposure compared to 21 hours later however, no baseline sample was obtained prior to exposure. If historic formaldehyde and formic acid baseline levels were assumed, then a closer examination of these data indicates that more formaldehyde (and metabolite) was excreted in the urine than could have possibly been absorbed by inhalation, indicating another route of exposure (perhaps dermal), or co-exposure to another chemical that also has formate as a metabolite (e.g., methanol), or higher personal exposures than were actually measured. There was also no indication that the urine formate levels were adjusted to compensate for urine specific gravity using urine creatinine levels, which may have markedly influenced the test results. 

The most commonly used criteria for the diagnosis of Balkan nephropathy are those proposed by Danilovic et al [99]. They include (1) farmers in the endemic villages, (2) familial history positive for endemic nephropathy, (3) mild proteinuria, (3) low specific gravity of the urine, (4) anemia, early occurrence, normochromic or hypochromic, (5) retention of nitrous compounds in the blood (urea > 50 mg/dl, creatinine > 1.5 mg/dl), (6) symmetrically shrunken kidneys. Using these criteria, Danilovic classified patients into the following groups ... 

The specific gravity of a patient s urine sample was measured to be 1.008. Given that the density of water is 1.000 g/mL at 4°C, what is the density of the urine sample ... 

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