anion gap

(redirected from cation-anion difference)

gap

 [gap]
an opening or hiatus.
anion gap the concentration of plasma anions not routinely measured by laboratory screening, accounting for the difference between the routinely measured anions and cations and equal to the plasma sodium − (chloride + bicarbonate); used in the evaluation of acid-base disorders.
auscultatory gap a period in which Korotkoff sounds disappear during auscultation of a patient' s blood pressure.

an·i·on gap

the difference between the sum of the measured cations and anions in the plasma or serum calculated as follows: ([Na+ + [K+]) - ([Cl-] + [HCO3-]) = < 20 mmol/L. Elevated values may occur in diabetic or lactic acidosis and in various types of poisoning; normal or low values occur in bicarbonate-losing metabolic acidoses.

anion gap

the difference between the concentrations of serum or plasma cations and anions, determined by measuring the concentrations of sodium cations and chloride and bicarbonate anions. It is helpful in the diagnosis and treatment of acidosis, and it is estimated by subtracting the sum of chloride and bicarbonate concentrations in the plasma from that of sodium. It is normally about 8 to 14 mEq/L and represents the negative charges contributed to plasma by unmeasured ions or ions other than those of chloride and bicarbonate, mainly phosphate, sulfate, organic acids, and plasma proteins. Anions other than chloride and bicarbonate normally constitute about 12 mEq/L of the total anion concentration in plasma. Acidosis can develop with or without an associated anion increase. An increase in the anion gap often suggests diabetic ketoacidosis, drug poisoning, renal failure, or lactic acidosis and usually warrants further laboratory tests.

anion gap

A mathematic approximation of the difference between unmeasured anions (PO4–, SO4–, proteins and organic acids) and unmeasured cations (Ca2+, Mg2+), with the former usually exceeding the latter. The anion gap is the difference between the sum of the most abundant measured serum anions (Cl­– and HCO3–) and serum cations (Na+, K+). Urinary AG is calculated as (Na+) + (K+) – (Cl–); it is a crude index of the levels of urinary ammonium and used to evaluate hyperchloremic metabolic acidosis.
 
Specimen
Serum, heparinised plasma.
 
Ref range
8–16 mEq/L.

Increased anion gap
Renal failure due to defective renal tubular acidification, with an increase in phosphate and sulfate; starvation-related ketoacidosis due to an accumulation of acetoacetate and beta-hydroxybutyrate, or alcohol abuse; in disorders of amino acid metabolism and hyperglycaemic nonketotic coma due to various organic acids; in lactic acidosis, overdoses or poisoning (e.g., salicylates, methanol ethylene glycol antifreeze or paraldehyde).

Decreased anion gap
Hypermagnesaemia; GI loss of bicarbonate; in nephrotic syndrome due to a loss of albumin, which is anionic at a physiologic pH; after lithium ingestion; and in myeloma and Waldenström’s macroglobinaemia, due to an increase in cationic proteins.

anion gap

Lab medicine A mathematic approximation of the difference between unmeasured anions–PO4–, SO4–, proteins and organic acids, and unmeasured cations-Ca2+, Mg2+, which normally exceed unmeasured cations; the AG is the difference between the sum of the most abundant measured serum anions–Cl– and HCO3– and serum cations–Na+ and K+; urinary AG is calculated as Na+ + K+ – Cl– and is a crude index of the levels of urinary ammonium and used to evaluate hyperchloremic metabolic acidosis Ref range 8-16 mEq/L; AG is ↑ in renal failure due to defective renal tubular acidification with an ↑ in phosphate and sulfate, starvation-related DKA due to an accumulation of acetoacetate and β-hydroxybutyrate or alcohol abuse, in disorders of amino acid metabolism and hyperglycemic nonketotic coma due to various organic acids, in lactic acidosis, overdose or poisoning—eg salicylates, methanol ethylene glycol antifreeze or paraldehyde; AG is ↓ in hypermagnesemia, GI loss of bicarbonate, in nephrotic syndrome due to a loss of albumin which is anionic at a physiological pH, after lithium ingestion, and multiple myeloma and Waldenström's macroglobinemia, due to an ↑ in cationic proteins

an·i·on gap

(an'ī-on gap)
The arithmetic difference between the concentrations of routinely measured cations (Na+ + K+) and of routinely measured anions (Cl- + HCO3-) in plasma or serum; unmeasured anions (phosphate, sulfate, protein, other organic ions) account for the gap, which is increased in metabolic acidosis due to diabetic ketosis, renal failure, or extraneous substances (methanol, salicylate).

anion gap

method used to evaluate a patient's acid-base status; based on the observation that the sum of blood cations (sodium, potassium, chloride and bicarbonate ions) usually exceeds the sum of the anions (sulfates, phosphates, proteinates, organic acid ions); the difference between the two is the anion gap. Significant departure from the normal level of difference indicates acid-base disturbance.
References in periodicals archive ?
Because the difference of Ca metabolism between animals, the responses of blood PTH, CT and BGP concerned with Ca metabolism to the DEB or dietary cation-anion difference (DCAD) varied.
Relationships between dry matter intake and acid-base status of lactating dairy cows as manipulated by dietary cation-anion difference.
The management of the dietary cation-anion difference (DCAD) became a worldwide practice to evaluate the risks of occurrence of milk fever and to optimize dairy cattle performances.
Our results, in addition to those of Meschy and Peyraud [5], seem adequate to advocate the use of EB for ration evaluation with regard to their cation-anion difference.
Its wide range includes the flagship bypass fat product, MEGALAC , and its variants, rumen fermentation enhancers, such as FERMENTEN , dietary cation-anion difference (DCAD) balancers, and rumen buffers, among others.
Dietary cation-anion difference has a role in animal productivity and health via its influence on the acid-base balance and calcium metabolism in the animal that often become 'broken' in dairy cows (Sanchez, 2003).
It is also reported that ruminants' kidneys are highly sensitive to blood cation-anion difference and increase the excretion of Ca during acidosis, independent of the hormonal action usually associated with Ca metabolism (Stacy and Wilson, 1970).
Manipulation of dietary cation-anion difference on nutritionally related production diseases, productivity, and metabolic responses of dairy cows.
The effect of cation-anion difference on calcium requirement, feed intake, body weight gain, and blood gasses and mineral concentrations of dairy calves.
Calcium and cation-anion difference effects on feed intake, body weight gain, and humoral response of dairy calves.
ABSTRACT : Influence of -110, +110, +220 and +330 mEq/kg of dry matter (DM) dietary cation-anion difference (DCAD) on growth performance of Thalli lambs were examined in a randomized complete block design.
Recent advances in mineral nutrition suggest that difference between certain cations (Na and K) and anions (Cl and S), usually referred as dietary cation-anion difference (DCAD), are of more significance for animal productivity than their individual effects (Tucker et al.

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