- ratio
- An
*expression*of the*relation*of one quantity to another ( e.g., of a proportion or rate). SEE ALSO:*index*(2),*quotient*. [L. r. (ration-) a reckoning, reason, fr. reor, pp. ratus, to reckon, compute]-the*absolute**terminal**innervation*r.*number*of*motor*endplates divided by the*number*of*terminal*axons related to them.-(*accommodative*convergence-*accommodation*r.*AC/A*) the amount of*convergence*(measured in*prism*diopters of*convergence*) divided by the amount of*accommodation*(measured in diopters) required to direct both eyes upon an*object*.-**A/G r.**abbreviation for albumin-*globulin*r..-**albumin-**(A/G r.) the r. of*globulin*r.*albumin*to*globulin*in the*serum*or in the*urine*in*kidney**disease*; the*normal*r. in the*serum*is approximately 1.55.-**ALT:AST r.**the r. of*serum**alanine aminotransferase*to*serum**aspartate*aminotransferase; elevated*serum*levels of both enzymes characterize*hepatic**disease*; when both levels are abnormally elevated and the ALT:AST r. is greater than 1.0, severe*hepatic**necrosis*or*alcoholic**hepatic**disease*is likely; when the r. is less than 1.0, an*acute*nonalcoholic*hepatic**condition*is favored.-**amylase-**a*creatinine**clearance*r.*test*for the*diagnosis*of*acute**pancreatitis*; it is determined by measuring*amylase*and*creatinine*in*serum*and*urine*; in apparently*healthy*individuals the*renal**clearance*of*amylase*is less than 5% that of*creatinine*; in*acute**pancreatitis*the r. is said to be greater than 5%.-**cardiothoracic r.**the r. of the horizontal*diameter*of the*heart*to the inner*diameter*of the rib*cage*at its widest*point*as determined on a*chest**roentgenogram*.-**r. of decayed and filled surfaces**(*RDFS*) an*index*of decayed and filled permanent surfaces per person, per full*complement*of 122*tooth*surfaces.-**r. of decayed and filled**(*teeth**RDFT*) an*index*of decayed and filled permanent*teeth*per person, per full*complement*of 28*teeth*.-(E) the*extraction*r.*fraction*of a*substance*removed from the*blood*flowing through the*kidney*; it is calculated from the*formula*(A —V)/A, where*A*and*V*, respectively, are the concentrations of the*substance*in*arterial*and*renal**venous**plasma*.-a*fertility*r.*measure*of the*fertility*of a*population*based on the*female**population*in the child-bearing age*group*, defined as ages 15–49 years.-the*functional**terminal**innervation*r.*number*of*muscle*fibers divided by the*number*of axons that innervate them.-in a radiographic scatter-absorbing*grid*r.*grid*, the r. of the*height*to the*width*of the gaps between*lead*strips; a higher*grid*r. removes more scattered*radiation*but requires more careful*x-ray**tube*positioning to avoid*grid*cutoff of the*primary**radiation**beam*.-**gyromagnetic r.**in*nuclear**magnetic**resonance*, the r. of the*magnetic**dipole**moment*of the*nucleus*to the*nuclear*spin angular momentum; the gyromagnetic r. is a unique*value*for each*type*of*nucleus*. SYN: magnetogyric r..-the r. of the*hand*r.*length*of the*hand*(measured on the*dorsum*from the*styloid**process*of the*ulna*to the tip of the third*finger*) to the*width*across the knuckles.-**international normalized r.**(INR) the*prothrombin**time*r. that would have been obtained if a*standard**reagent*had been used in a*prothrombin**time**determination*; the*prothrombin**time*r. is expressed as the*patient**prothrombin**time*divided by the*mean*of the*prothrombin**time*reference*interval*; the*prothrombin**time*r. is obtained for a working*reagent*in the*laboratory*through use of a*parameter*designated the international*sensitivity**index*. SEE ALSO: international*sensitivity*index.-**IRI/G r.**the r. of*immunoreactive**insulin*to*serum*or*plasma*glucose; in*hypoglycemic*states a r. of less than 0.3 is usual, with the exception of the*hypoglycemia*due to*insulinoma*, where the r. is often higher than 0.3.-**K:A r.**abbreviation for ketogenic-*antiketogenic*r..-**ketogenic-**(K:A r.) the proportion between substances that*antiketogenic*r.*form*ketones in the*body*and those that*form**d-glucose*.-**lecithin/sphingomyelin r.**(L/S r.) a r. used to determine*fetal**pulmonary**maturity*, found by*testing*the*amniotic**fluid*; when the lungs are*mature*,*lecithin*exceeds sphingomyelin by 2 to 1.-**L/S r.**abbreviation for lecithin/sphingomyelin r..-**magnetogyric r.**(mag′ne-to-gy-rik) SYN: gyromagnetic r..-**mass-**the r. of the*action*r.*product*of all of the*product*concentrations divided by the*product*of all of the*reactant*concentrations of a particular*reaction*; when the*reaction*has been completed ( i.e.,*t*= ∞), then this r. is equal to the*equilibrium**constant*.-**M:E r.**the r. of*myeloid*to*erythroid*precursors in*bone**marrow*; normally it varies from 2:1 to 4:1; an increased r. is found in infections,*chronic**myelogenous**leukemia*, or*erythroid**hypoplasia*; a decreased r. may*mean*a*depression*of*leukopoiesis*or normoblastic*hyperplasia*depending on the overall*cellularity*of the*bone**marrow*.-the r. of*mendelian*r.*progeny*with particular phenotypes or genotypes*expected*in accordance with*Mendel*law among the offspring of matings specified as to*genotype*or*phenotype*.-**nuclear-**r. of*cytoplasmic*r.*volume*of*nucleus*to*volume*of*cytoplasm*, fairly*constant*for a particular*cell**type*and usually increased in*malignant*neoplasms.-**nucleolar-**r. of*nuclear*r.*volume*of*nucleolus*to*volume*of*nucleus*, usually increased in*malignant*neoplasms.-**P/O r.**a*measure*of*oxidative**phosphorylation*; the r. of*phosphate*radicals esterified (forming*adenosine 5′-triphosphate*from*adenosine 5′-diphosphate*) to atoms of*oxygen*consumed by*mitochondria*; normally, the r. is 3 (starting from NADH). SYN: P/O quotient.-the r. of the net*respiratory**exchange*r.*output*of*carbon**dioxide*to the simultaneous net*uptake*of*oxygen*at a given*site*, both expressed as moles or*STPD*volumes per*unit**time*; in the steady*state*,*respiratory**exchange*r. is equal to the*respiratory**quotient*of*metabolic*processes.-in*segregation*r.*genetics*, the proportion of*progeny*of a particular*genotype*or*phenotype*from actual matings of specified genotypes. The*test*of a*mendelian**hypothesis*is the comparison of the*segregation*rate with the*mendelian*rate.-**sex r.****1.**the r. of*male*to*female**progeny*at some specified*stage*of the*life**cycle*, notably at*conception*(primary), at*birth*(secondary), or at any*stage*between*birth*and*death*(tertiary);**2.**the r. of the numbers of males to females affected by a particular*disease*or*trait*.-**signal-to-**the relative*noise*r.*intensity*of a*signal*to the*random**variation*in*signal**intensity*, or*noise*; used to evaluate many*imaging*techniques and*electronic*systems.-**standardized**the r. of the*mortality*r.*number*of events observed in a*population*to the*number*that would be*expected*if the*population*had the same*distribution*as a*standard*or reference*population*.-**systolic/diastolic r.**a calculation from pulsed*Doppler**ultrasound*determinations of*blood**flow*velocities that reflects*intrinsic**resistance*in an*arterial**blood vessel*.-the r. of the maximally tolerated*therapeutic*r.*dose*of a*drug*to the minimal*curative*or effective*dose*; LD_{50}divided by*ED*._{50}-(F) the*variance*r.*distribution*of the r. of two independent estimates of the same*variance*from a*gaussian**distribution*based on samples of sizes (*n*+ 1) and (m + 1), respectively. Estimates are usually based on one such*sample*analyzed in such a way as to make them independent, e.g.,*analysis*of*variance*, and F may be used to*test*a null*hypothesis*that the observed differences among*sample*means is no greater than could readily be accounted for by chance.-**ventilation/perfusion r.**(*Va/Q*) the r. of*alveolar**ventilation*to simultaneous*alveolar**capillary**blood**flow*in any*part*of the*lung*; because both*ventilation*and*perfusion*are expressed per*unit**volume*of*tissue*and per*unit**time*, which cancel, the units become liters of gas per*liter*of*blood*.-**waist-hip r.**r. of the*abdominal**circumference*at the*navel*to*maximum*hip and*buttocks**circumference*.-(ZSR) the r. of the*zeta**sedimentation*r.*zetacrit*to the*hematocrit*, normally 0.41–0.54 (41–54%); it is a*sensitive**indicator*of the*erythrocyte**sedimentation**rate*(ESR) and, unlike the latter, is unaffected by*anemia*, which tends to elevate the ESR.* * *

**ra·tio 'rā-(.)shō, -shē-.ō***n*,*pl***ra·tios**the relationship in quantity, amount, or size between two or more things*see***SEX RATIO*** * *

ra·tio (raґshe-o) [L.] an expression of the quantity of one substance or entity in relation to that of another; the relationship between two quantities expressed as the quotient of one divided by the other.

*Medical dictionary.
2011.*