The kidney glomerulus filters blood mainly based on particle size to produce a filtrate lacking cells or large proteins. Most of the ions and molecules in the filtrate are needed by the body and must be reabsorbed farther down the nephron tubules, resulting in the formation of urine. Urine characteristics change depending on water intake, exercise, environmental temperature, and nutrient intake. Urinalysis analyzes characteristics of the urine and is used to diagnose diseases. A minimum of 400 to 500 mL urine must be produced daily to rid the body of wastes. Excessive quantities of urine may indicate diabetes insipidus or diabetes mellitus. The pH range of urine is 4.5 to 8.0, and is affected by diet. Osmolarity ranges from 50 to 1200 milliosmoles, and is a reflection of the amount of water being recovered or lost by renal nephrons.
anuria
absence of urine produced; production of 50 mL or less per day
leukocyte esterase
enzyme produced by leukocytes that can be detected in the urine and that serves as an indirect indicator of urinary tract infection
oliguria
below normal urine production of 400–500 mL/day
polyuria
urine production in excess of 2.5 L/day; may be caused by diabetes insipidus, diabetes mellitus, or excessive use of diuretics
specific gravity
weight of a liquid compared to pure water, which has a specific gravity of 1.0; any solute added to water will increase its specific gravity
urinalysis
analysis of urine to diagnose disease
urochrome
heme-derived pigment that imparts the typical yellow color of urine
1. Diabetes insipidus or diabetes mellitus would most likely be indicated by ________.
A) anuria
B) polyuria
C) oliguria
D) none of the above
B
2. The color of urine is determined mainly by ________.
A) diet
B) filtration rate
C) byproducts of red blood cell breakdown
D) filtration efficiency
C
3. Production of less than 50 mL/day of urine is called ________.
A) normal
B) polyuria
C) oliguria
D) anuria
D
1. What is suggested by the presence of white blood cells found in the urine?
The presence of white blood cells found in the urine suggests urinary tract infection.
2. Both diabetes mellitus and diabetes insipidus produce large urine volumes, but how would other characteristics of the urine differ between the two diseases?
Diabetes mellitus would result in urine containing glucose, and diabetes insipidus would produce urine with very low osmolarity (low specific gravity, dilute).