Search Results for: osmolality

Quick test interpretation

Chemistry /

…emia (uncommon) Iatrogenic Diuretic therapy, hypotonic fluid administration, mannitol (solvent drag from hyperosmolality) Hyperosmolar states (solvent drag) Diabetes mellitus Volume overload (hypervolemic hyponatremia with inappropriate ADH release due to perceived volume depletion) Congestive heart failure, hepatic disease, nephrotic syndrome, advanced renal failure Hypotonic or isotonic fluid losses with dilution (ADH or drinking) or hy…

Quick test interpretation Read More »

Quick test interpretation

Hematology /

…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…

Quick test interpretation Read More »

Ocular fluids

Chemistry /

…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…

Ocular fluids Read More »

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…

Renal conservation of water Read More »

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…

Renal concentrating ability Read More »

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….

Response to changes in tonicity Read More »

Scroll to Top