Renal Function

diet, physical activity, health

principal organ for regulating body fluid composition

renal excretion

kidney function (creatinine and urea)

how much plasma is being filtered at glomerulus

1. polyuria
2. oliguria
3. nocturia
4. anuria

greater than 3L / day

a. conditions with water diuresis (osmolality <200 mOs / kg)
b. conditions with solute diuresis (osmolality >=300 mOs / kg)

ADH secretion inadequate or receptors ineffective

glucose, urea, or sodium

less than 400 mL / day

diseases that affect nephrons, glomerulonephritis

urinary obstruction, tubular dysfunction, fluid loss

prostatic hyperplasia: prostate enlarges surrounding urethra, urine can't fully empty, constant urge to urinate

no urine ; indicates progressive renal disease or renal failure

high glucose -> body cannot process and glucose goes into urine, glucose is osmotically active, pulling in more water with it

solute number (not weight)

in distal and collecting tubules when ADH is present

275-300 mOsm / kg

1-3 times

number of molecules and SIZE of molecules

DI water

1.002 - 1.035

urea, chloride, sodium

concentrating ability slowly diminished until specific gravity or osmolality are unchanging

cannot change specific gravity and osmolality

measure serum and urine osmolality (after fasting and no water intake)

increase because kidney would reserve H2O (in healthy pt)

1. neurogenic
2. nephrogenic

diabetes insipidus (ADH decreased due to problem with ADH production in brain)

diabetes insipidus (problem with receptors in kidney, normal ADH is still being produced)

compare with plasma concentration or administer ADH to see if that changes urine osmolality

decreases, urine volume increases

increases, urine volume decreases (to absorb as much of the water as possible)

volume of plasma in mL that is completely cleared of a substance per unit of time

volume and composition of urine excreted

(urine concentration * volume of urine)/ plasma concentration of substance

tests for GFR using substances that are solely by glomerular filtration

waste product in muscles, produced at relatively constant rate

1. timed specimen (usually 24 hr)
2. urine creatinine (U) and plasma creatinine (P)
3. urine volume
4. body surface area (BSA)

small amt of creatinine secreted by tubules (7-15%), resulting in increased urine concentration of creatinine.
However, using Jaffe reaction: colorimetric overestimation of creatinine 7-10%

(urine creatinine/serum creatinine) * (urine volume / 1440 mins) * (1.73/BSA)

older people

0.5 to 1.5 mg/dL

adjust for body surface area (BSA)
(BSA usually 1.73 for average size adult)

low molecular weight protein found on surface of nucleated cells and shed into plasma
99.9% should be reabsorbed by PCT

reduced tubular function when It is increased in urine (means PCT is not absorbing, possibly Fanconi syndrome)

1. identifies early kidney transplant rejection
2. differentiate tubular and glomerular disease

continually produced protein that is broken down by PCT

long-term monitoring of renal function

independent of muscle mass, height, weight, etc.
Able to determine GFR without individual variables

decreased glomerular function

early diabetic nephropathy

increased glomerular permeability

hyperglycemia

damage overtime makes large holes in between podocytes allowing larger molecules to go through

exogenous nontoxic weak acid secreted almost exclusively by PCT, indicator of renal tubular secretory function

assess tubular function for removing acids (ability to control pH balance)

give ammonium chloride and measure series of urine pH and plasma bicarbonate. Used to diagnose renal tubular acidosis

ammonium chloride breaks down to urea CH4NO2 and HCL; therefore, pH SHOULD decrease and become more acidic

glomerular filtration rate (GFR)

tubular concentrating ability

glomerular permeability to plasma proteins

spikes or peaks in gamma protein that can indicate monoclonal or multiclonal diseases (like multiple myeloma)

cancer of B lymphocytes

large singular peak at gamma protein due to clonal disease