Search Results for: osmolality

Quick test interpretation

…  Interpret with: Electrolytes (K+, Cl–), urinalysis, HCT, protein, urea nitrogen, creatinine, osmolality       Potassium Increased   Artifact Serum K+ > plasma K+ (release from WBC, platelets); anticoagulant (K+ EDTA), hemolysis (horses, camelids, some cattle, some breeds of dogs, pigs), leukocytosis (release from cells with clotting), age (> foals), K administration and intravenous (IV) li…

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Quick test interpretation

…False increases in MCV (HCT is a calculated value): Uptake of water with storage (delayed processing) or hyper-osmolality (hypernatremia, hyperglycemia etc), agglutination Relative change to blood water Dehydration (common), splenic contraction (horses particularly) Absolute ↑ in RBC mass Primary polycythemia (polycythemia vera or chronic erythroid leukemia, rare), secondary polycythemia due to appropriate secretion of erythropoietin (hypoxi…

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Ocular fluids

…lectrolyte and mineral concentrations in aqueous versus vitreous fluid. One study in cattle showed that sodium, osmolality and phosphate concentrations were higher (particularly phosphate) whereas potassium, calcium and magnesium concentrations were slightly lower in aqueous fluid, respectively. Potassium and calcium concentrations increased in both fluids, with higher increases in aqueous fluid, after 24 hours of storage refrigerated. In contras…

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Renal conservation of water

…of tonicity of the medulla). This is accomplished as follows: 1. Normally the glomerular filtrate has a similar osmolality to plasma (300 mOsmol/kg). In the descending limb of the loop of Henle, the NaCl cannot be absorbed, but water is passively resorbed (#1), creating a hypertonic urine (>1200 mOsmol/kg) as it enters the ascending limb. 2. When this NaCl-rich fluid enters the NaCl-permeable (water-impermeable) thin ascending limb in the inner m…

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Renal concentrating ability

…is accomplished as follows: 1. Descending limb of loop of Henle: Normally the glomerular filtrate has a similar osmolality to plasma (300 mOsmol/kg). In the descending limb of the loop of Henle, the NaCl cannot be absorbed, but water is passively resorbed (#1), creating a hypertonic urine (>1200 mOsmol/kg) as it enters the ascending limb. 2. Thin ascending limb of the loop of Henle: When this NaCl-rich fluid enters the NaCl-permeable (water-imper…

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Response to changes in tonicity

…ng volume) by stimulating ADH release (causing water retention in the kidneys without sodium) and thirst (water gain without sodium). This will dilute out the sodium, decreasing tonicity. Conversely, with decreased tonicity (decreased effective osmolality), usually due to hyponatremia, osmoreceptors in the hypothalamus inhibit ADH secretion (promoting water loss) and thirst (preventing water gain), which serves to increase sodium concentrations….

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