Urine output, normal

Fluid balance in the body is maintained or restored primarily by variations in urine output. Normally, this amounts to about 1400 mL/day, but the total excretion fluctuates according to water intake. The primary factor that controls urine production is the rate of water reabsorption from the renal tubules in the kidneys. This rate is regulated chiefly by the pituitary hormone vasopressin and by the adrenal cortex hormone aldosterone. 

Maintain intravascular volume status and urine output with normal saline... 

Organ dysfunction reversal evident by increased urine output to greater than 0.5 mL/kg per hour (1.0 mL/kg per hour in pediatrics), return of mental status to baseline, and normalization of skin color and temperature over the first 24 hours ... 

Fluid restriction is generally unnecessary as long as sodium intake is controlled. The thirst mechanism remains intact in CKD to maintain total body water and plasma osmolality near normal levels. Fluid intake should be maintained at the rate of urine output to replace urine losses, usually fixed at approximately 2 L/day as urine concentrating ability is lost. Significant increases in free water intake orally or intravenously can precipitate volume overload and hyponatremia. Patients with stage 5 CKD require renal replacement therapy to maintain normal volume status. Fluid intake is often limited in patients receiving hemodialysis to prevent fluid overload between dialysis sessions. 

The patient is started on fluconazole 400 mg/day, but 3 days later has persistent fever and develops hypotension and decreased urine output. Blood cultures reveal a germ tube-negative yeast growing in the blood. Laboratory studies revealed a white blood cell count of 12,300/mm3 (12x109/L), aspartate aminotransferase 68 IU/L (1.13 pKat/L), alanine aminotransferase 75 IU/L (1.25 pKat/L), alkaline phosphatase 168 IU/L (2.8 pKat/L), and normal bilirubin. Serum creatinine is 1.8 mg/dL (159 pmol/L). 

Continuous bladder irrigation by catheterization uses normal saline at 250 to 1000 mL/hour to flush acrolein from the bladder. Hyperhydration with normal saline at 3 L/m2 per day with intravenous furosemide to maintain urine output greater than 100 mL/hour also has been used with cyclophosphamide. Mesna is equivalent to both strategies in patients receiving high-dose cyclophosphamide and avoids the discomfort and... 

Vigorous intravenous hydration with dextrose 5% in water with half-normal saline at 3 L/m2 per day to maintain a urine output of 100 mL/m2 per hour or more is necessary, unless the patient presents with acute renal dysfunction. Alkalinization of the urine to a pH of 7.0 or more with 50 to 100 mEq/L of sodium bicarbonate has been used to promote uric acid solubility for excretion. This measure is controversial because xanthine and hypoxanthine are less soluble at alkaline pH, potentially leading to crystallization, especially during and after allopurinol therapy32 (see Fig. 96-6). Medications that increase serum... 

The granular cells that secrete renin also serve as intrarenal baroreceptors, monitoring blood volume and blood pressure in the afferent arterioles. Arteriolar pressure and renin secretion have an inverse relationship in other words, an increase in blood volume causes an increase in arteriolar blood pressure increased stimulation of the intrarenal baroreceptors and decreased secretion of renin. With less angiotensin Il-induced vasoconstriction of the afferent arteriole, RBF, GFR, and urine output will increase so that blood volume returns to normal. 

The osmoreceptors of the hypothalamus monitor the osmolarity of extracellular fluid. These receptors are stimulated primarily by an increase in plasma osmolarity they then provide excitatory inputs to the thirst center and the ADH-secreting cells in the hypothalamus. The stimulation of the thirst center leads to increased fluid intake. The stimulation of the ADH-secreting cells leads to release of ADH from the neurohypophysis and, ultimately, an increase in reabsorption of water from the kidneys and a decrease in urine output. These effects increase the water content of the body and dilute the plasma back toward normal. Plasma osmolarity is the major stimulus for thirst and ADH secretion two additional stimuli include ... 

Successful fluid resuscitation should increase SBP (greater than 90 mm Hg), Cl (greater than 2.2 L/min/m2), and urine output (0.5 to 1 mL/kg/hour) while decreasing SVR to the normal range. MAP greater than 60 mm Hg should be achieved to ensure adequate cerebral and coronary perfusion pressure. 

Fic. 2. Chromatogram of normal adult female subject (urinary amino acids, daily output at mid-cycle 1,010 ml/24 hr sample 2 ml). Elution curve from Dowex 50-X5 of free amino acids and closely related substances. Peaks Xu X2 and Yj, Y2 are found regularly but correspond to unknown substances they do not disappear after hydrolysis. The peak marked peptide in the region near fraction 410 is usually present and disappears after hydrolysis. The one at fraction 325 also disappears after hydrolysis, but its presence was seen only once in a group of more than 50 different samples of urines of normal subjects, including cases of pregnancy (Soupart, footnote p. 223). Amino acids in brackets are usually found but were practically absent from die present sample of urine. 

The urine creatinine concentration should be used to normalize the quantity of any analyte of interest, as this will correct for incomplete urine collection or urine dilution that may have resulted from drinking water spillage within the metabolism cages (Haas et al. 1997). The quantity of creatinine in a spot urine sample serves as an accurate index of the 24 hour urine output in most species. 

Glucose and saline are administered intravenously to maintain blood glucose in the normal range, to ensure that the patient is adequately hydrated and has a urine output. 

Add 50 to 100 mEq of sodium bicarbonate to one liter of 5% dextrose in 0.25 normal saline and administer intravenously at a rate that maintains urine output at 2 to 3 mL/kg/hour maintain alkaline urine (i.e., pH >7.5) until urine is hemoglobin free. 

Overdose is treated by use of i.v. fluid to maintain a good urine output guided by frequent measurement of plasma electrolytes and osmolality. Hyper-natraemia indicates probable diabetes insipidus and isotonic dextrose should then be used until plasma sodium concentration and osmolality become normal. Isotonic saline foriirs part of the fluid regimen (but overuse may result in hypematrae-mia) and potassium supplement will be required. Haemodialysis is effective but may have to be repeated frequently as plasma concentration rises after acute reduction (due to equilibration as lithium leaves cells and also by continued absorption from sustained-release formulahons). 

The prevalence of polyuria among unselected lithium-treated patients has been difficult to ascertain [11]. Polyuria, as defined by a 24-hour urine output exceeding 3 L, varies considerably among patients on chronic Uthium therapy [67-80]. In a review of a total of 841 unselected patients evaluated for 24-hour urine volume, we found that 160 (or 19%) had polyuria as defined by fhese criferia [11]. If was found fhat 85% of hthium treated patients have a normal glomerular filtration rate and that the remaining 15% have only mild reductions in renal function [11]. After fluid deprivation of approximately 24-hours duration, normal individuals should be able to raise urinary osmolahty above 800 mOsm/kg HjO. In a survey of a total of 1,105 lithium-treated patients [69-74], we found that at least 602 (or 54%) had a subnormal concentrating ability defined by this criterion [11]. 

To overcome these limitations, furosemide (frusemide) can be given at higher doses intravenously (i.v.) or as an i.v. infusion (Dishart Kellum 2000). In normal horses, the i.v. administration of furosemide (frusemide) produces a dose-dependent increase in urine output, up to a maximum dose rate of about 5 mg/kg (Garner... 

Moderate 1-3 Moist or slightly tacky Normal (<2 s) Normal Decreased urine output... 

Fasting venous blood, drawn with a patient at rest, has a pyruvate concentration of 0.03 to O.lOmmol/L (0.3 to 0.9mg/dL). Arterial blood contains 0.02 to 0.08mmol/L (0.2 to 0,7mg/dL). Values for CSF are 0.06 to 0.19mmol/L (0,5 to 1.7mg/dL), Age-related reference intervals in CSF have been estabfished in children. Urine output of pyruvate is normally Immol/day or less. There are few clinical indications for measurement of blood pyruvate concentrations. 

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