Medical Dictionary banner
Medical Dictionary - Dictionary of Medicine and Human Biology

Medical Dictionary


hypoproteinosis (hi′po-pro′te-in-o′sis, -pro′ten-)
A condition, especially in children, due to a dietary deficiency of protein; characterized by anorexia, vomiting, retardation of growth, anemia, and increased susceptibility to infections.

hypoprothrombinemia (hi′po-pro-throm′bin-e′me-a)
Abnormally small amounts of prothrombin in the circulating blood. SYN: prothrombinopenia.

hypoptyalism (hi′po-ti′a-lizm)
SYN: hyposalivation. [hypo- + G. ptyalon, saliva]

hypopyon (hi-po′pi-on)
The presence of leukocytes in the anterior chamber of the eye. [hypo- + G. pyon, pus] recurrent h. SYN: Behçet syndrome.

hyporeflexia (hi′po-re-flek′se-a)
A condition in which the reflexes are weakened.

hyporeninemia (hi′po-ren-i-ne′me-a)
Low levels of renin in the circulating blood.

hyporeninemic (hi′po-ren-i-ne′mik)
Denoting or characterized by hyporeninemia.

hyporiboflavinosis (hi′po-ri′bo-fla-vi-no′sis)
A more correct term than the more commonly used ariboflavinosis, q.v.

hyposalivation (hi′po-sal′i-va′shun)
Reduced salivation. SYN: hypoptyalism.

hyposcheotomy (hi-pos-ke-ot′o-me)
Incision or puncture into a hydrocele at its most dependent point. [hypo- + G. oscheon, scrotum, + tome, incision]

hyposcleral (hi-po-skler′al)
Beneath the sclerotic coat of the eyeball.

hyposensitivity (hi′po-sen-si-tiv′i-te)
A condition of subnormal sensitivity, in which the response to a stimulus is unusually delayed or lessened in degree.

SYN: desensitization.

hyposkeocytosis (hi′po-ske′o-si-to′sis)
SYN: hyponeocytosis. [hypo- + skaios, left, + kytos, cell, + -osis, condition]

hyposmia (hi-poz′me-a)
Diminished sense of smell. It may be: 1) general to all odorants, partial to some odorants, or specific to one or more odorants; 2) due to transport disorders (in nasal obstruction) or to sensorineural disorders (affecting the olfactory neuroepithelium or the central olfactory neural pathways); and 3) hereditary or acquired. SYN: olfactory hypesthesia. [hypo- + G. osme, smell]

hyposmosis (hi-pos-mo′sis)
A reduction in the rapidity of osmosis.

hyposmotic (hi-pos-mot′ik)
Having an osmolality less than another fluid, ordinarily assumed to be plasma or extracellular fluid.

hyposomatotropism (hi′po-so′ma-to-tro′pizm)
A state characterized by deficient secretion of pituitary growth hormone (somatotropin).

hyposomia (hi′po-so′me-a)
Inadequate development of the body. [hypo- + G. soma, body]

hyposomniac (hi′po-som′ne-ak)
A person with a reduction in sleep time. [hypo- + L. somnus, sleep]

hypospadiac (hi′po-spa′de-ak)
Relating to hypospadias.

hypospadias (hi′po-spa′de-as)
A developmental anomaly characterized by a defect on the ventral surface of the penis so that the urethral meatus is proximal to its normal glanular location; may be associated with chordee; also a similar defect in the female in which the urethra opens into the vagina. Cf.:epispadias. SYN: urogenital sinus anomaly. [hypo- + G. spao, to tear or gouge] balanic h. SYN: glanular h.. coronal h. ventral and proximal malposition of meatus in the coronal sulcus. glanular h. ventral and proximal glanular malposition of urethral meatus in a male. SYN: balanic h.. penile h. malposition of the urethral meatus on the ventral penile shaft. penoscrotal h. malposition of the urethral opening at the junction of the penis and scrotum. perineal h. h. in which the urethral meatus opens in the perineum near the anus; the scrotum is usually cleft. scrotal h. h. with the urethral opening on the scrotal surface. subcoronal h. malposition of the meatus in the coronal sulcus.

hyposphygmia (hi′po-sfig′me-a)
Abnormally low blood pressure with sluggishness of the circulation. [hypo- + G. sphyxis, pulse]

hyposplenism (hi′po-splen′izm)
Absent or reduced splenic function, usually due to surgical removal, congenital aplasia, tumor replacement, or splenic vascular accident. Red cell abnormalities, including the presence of inclusions, nucleated erythrocytes, and target cells, are commonly present. Patients with h. are at increased risk of bacterial sepsis, especially due to pneumococcus.

hypostasis (hi-pos′ta-sis)
1. Formation of a sediment at the bottom of a liquid. 2. SYN: hypostatic congestion. 3. The phenomenon whereby the phenotype that would ordinarily be manifested at one locus is obscured by the genotype at another epistatic locus; e.g., in humans, the phenotype for the ABO blood group locus can be expressed only in the presence of its precursor, H substance. The Bombay factor in the homozygous state blocks H formation and obscures the ABO phenotype. [G. hypo-stasis, a standing under, sediment] postmortem h. SYN: postmortem livedo. pulmonary h. hydrostatic congestion of the lung.

hypostatic (hi-po-stat′ik)
1. Sedimentary;resulting from a dependent position. 2. Relating to hypostasis.

hyposthenuria (hi′pos-the-noo′re-a)
Excretion of urine of low specific gravity, due to inability of the tubules of the kidneys to produce a concentrated urine; also occurs following excessive water ingestion in diabetes insipidus. [hypo- + G. sthenos, strength, + ouron, urine]

hypostome (hi′po-stom)
The central unpaired holdfast organ of the tick capitulum; the h. is covered with recurved spines that enable it to serve as an anchoring device while the tick feeds. [hypo- + G. stoma, mouth]

hypostomia (hi′po-sto′me-a)
A form of microstomia in which the oral opening is a small vertical slit. [hypo- + G. stoma, mouth]

hypostosis (hip-os-to′sis)
Deficient development of bone. [hypo- + G. osteon, bone, + -osis, condition]

hyposupradrenalism (hi′po-soo′pra-a-dre′nal-izm)
SYN: chronic adrenocortical insufficiency.

hyposystole (hi′po-sis′to-le)
A weak or incomplete cardiac systole.

hypotelorism (hi-po-tel′or-izm)
Abnormal closeness of eyes. [hypo- + G. tele, far off, + horizo, to separate, fr. horos, boundary]

hypotension (hi′po-ten′shun)
1. Subnormal arterial blood pressure. SYN: hypopiesis. 2. Reduced pressure or tension of any kind. [hypo- + L. tensio, a stretching] arterial h. h. (1) . idiopathic orthostatic h. the tendency for blood pressure to drop for unknown reasons on assuming upright posture. induced h., controlled h. deliberate acute reduction of arterial blood pressure to reduce operative blood loss by pharmacologic means during anesthesia and surgery. intracranial h. subnormal pressure of cerebrospinal fluid; most commonly following lumbar puncture and associated with headache, nausea, vomiting, stiffness of the neck, and sometimes fever; may also result from dehydration. orthostatic h. a form of low blood pressure that occurs in a standing posture. SYN: orthostatic hypopiesis, postural h.. postural h. SYN: orthostatic h..

hypotensive (hi′po-ten′siv)
Characterized by low blood pressure or causing reduction in blood pressure.

hypotensor (hi-po-ten′ser, -sor)
SYN: depressor (4) .

hypothalamohypophysial (hi′po-thal′a-mo-hi′po-fiz′e-al)
Relating to both the hypothalamus and the hypophysis.

hypothalamus (hi′po-thal′a-mus) [TA]
The ventral and medial region of the diencephalon forming the walls of the ventral half of the third ventricle; it is delineated from the thalamus by the hypothalamic sulcus, lying medial to the internal capsule and subthalamus, continuous with the precommissural septum anteriorly and with the mesencephalic tegmentum and central gray substance posteriorly. Its ventral surface is marked by, from before backward, the optic chiasma, the unpaired infundibulum that extends by way of the infundibular stalk into the posterior lobe of the hypophysis, and the paired mamillary bodies. The h. consists of the anterior hypothalamic area [TA], dorsal hypothalamic area [TA], intermediate hypothalamic area [TA], lateral hypothalamic area [TA], and posterior hypothalamic area [TA], each of these containing specific nuclei. It has afferent fiber connections with the mesencephalon, limbic system, cerebellum, and efferent fiber connections with the same structures and with the posterior lobe of the hypophysis; its functional connection with the anterior lobe of the hypophysis is established by the hypothalamohypophysial portal system. The h. is prominently involved in the functions of the autonomic (visceral motor) nervous system and, through its vascular link with the anterior lobe of the hypophysis, in endocrine mechanisms; it also appears to play a role in neural mechanisms underlying moods and motivational states. SEE ALSO: pituitary gland. [hypo- + thalamus]

hypothenar (hi′po-the′nar, hi-poth′e-nar) [TA]
1. [NA] SYN: h. eminence. 2. Denoting any structure in relation with the h. eminence or its underlying collective components. [hypo- + G. thenar, the palm]

hypothermal (hi-po-ther′mal)
Denoting hypothermia.

hypothermia (hi′po-ther′me-a)
A body temperature significantly below 98.6°F (37°C). [hypo- + G. therme, heat] accidental h. unintentional decrease in body temperature, especially in the newborn, infants, and elderly, particularly during operations. moderate h. a body temperature of 23–32°C. induced by surface cooling. profound h. a body temperature of 12–20°C. regional h. reduction of the temperature of an extremity or organ by external cold or perfusion with cold blood or solutions. total body h. the deliberate reduction of total body temperature, in order to reduce tissue metabolism.

hypothesis (hi-poth′e-sis)
A conjecture advanced for heuristic purposes, cast in a form that is amenable to confirmation or refutation by the conductance of definable experiments and the critical assembly of empiric data; not to be confused with assumption, postulation, or unfocused speculation. SEE ALSO: postulate, theory. [G. foundation, assumption fr. hypotithenai, to lay down] adaptor h. a h., proposed by F.H.C. Crick, that an adaptor molecule must be present between the information-containing DNA and the protein being synthesized. alternative h. in Neyman-Pearson testing of a h., the h. or family of hypotheses about the numerical value of a parameter if and only if the null h. is rejected as untenable. autocrine h. that tumor cells containing viral oncogenes may have encoded a growth factor, normally produced by other cell types, and thereby produce the factor autonomously, leading to uncontrolled proliferation. Avogadro h. SYN: Avogadro law. Bayesian h. an array of surmised values of a parameter to be severally explored in the light of a current set of data, with logical symmetry being preserved among all. The merits of each h. entertained are based on quantity, the prior probability. The probability of the data conditional on the h. is computed as the conditional probability for each; the product of the two for each h. is the joint probability, and the ratio of each joint probability to the sum of all the joint probabilities is the posterior probability for that h.. Unlike the Neyman-Pearson test of hypotheses, the answer is a statement about the h., not about the sample conditional on the h.. No h. is preferred or prevails by default. The procedure may be applied recursively any number of times, as the data becomes available. frustration-aggression h. the theory that frustration may lead to aggression, but that aggression is always the result of some form of frustration. gate-control h. SYN: gate-control theory. Goldie-Coldman h. a mathematic model that predicts that tumor cells mutate to a resistant phenotype at a rate dependent on their intrinsic genetic instability. The probability that a cancer would contain drug-resistant clones depends on the mutation rate and the size of the tumor. According to this h., even the smallest detectable cancers would contain at least 1 drug-resistant clone; therefore, the best chance of cure would be to use all effective chemotherapy drugs; in practice, this has meant using 2 different non–cross-resistant chemotherapy regimens in alternating cycles. Gompertz h. a theory that the force of mortality increases in geometrical progression, being based on the assumption that the average exhaustion of an individual's power to avoid death is such that at the end of equal infinitely small intervals of time the individual loses equal proportions of the power to oppose destruction that were available at the commencement of each of these intervals. insular h. obsolete theory of the origin of diabetes mellitus from destruction or loss of function of the islets of Langerhans in the pancreas. Knudsen h. an explanation for the bilateral (and earlier) occurrence of hereditary retinoblastoma; if one tumor suppressor gene is mutated by inheritance, only one somatic mutation is needed inactivate the other allele. In the sporadic form, 2 mutations, which inactivate each allele, are necessary. Lyon h. SYN: lyonization. Makeham h. a development of Gompertz h. as to the force of mortality following some mathematical law. Makeham assumed that death was the consequence of two generally coexisting causes: 1) chance; 2) a deterioration or increased inability to withstand destruction. The first of these is constant, the second is an increasing geometrical progression. Michaelis-Menten h. a h. that a complex is formed between an enzyme and its substrate (also known as the O'Sullivan-Tompson h.), which complex then decomposes to yield free enzyme and the reaction products (also referred to as the Brown h.), the latter step being the rate-determining step for the overall rate of substrate-product conversion. SEE ALSO: Michaelis-Menten constant, Michaelis-Menten equation. mnemic h. the theory that stimuli or irritants leave definite traces (engrams) on the protoplasm of the animal, and when these stimuli are regularly repeated they induce a habit which persists after the stimuli cease. SYN: mnemic theory, mnemism, Semon-Hering theory. monoamine h. the classical theory of the neurochemical basis of depression linking it to a deficiency of at least one of three monoamine neurotransmitters, norepinephrine, serotonin, or dopamine. Neyman-Pearson statistical h. a formal conjecture about the numerical value of a parameter to be tested exclusively in the light of an immediate set of data without attention to prior knowledge or convictions and ignoring other sets of evidence treated in a similar fashion. The answer is a statement not about whether the h. is true but whether it is an acceptable explanation of the data or should be rejected in favor of another h.. Norton-Simon h. h. that a tumor is composed of populations of faster-growing cells, which are sensitive to therapy, and slower-growing, more resistant cells. Since only therapy that completely eradicates all tumor cells will be curative, this is most likely to occur with sequential, non–cross-resistant regimens. The initial regimen must be effective enough to result in a low residual tumor burden and is followed by one or more non–cross-resistant treatments to eradicate the remainder of the cancer. null h. the statistical h. that one variable has no association with another variable or set of variables, or that two or more populations do not differ from each other; the statement that results do not differ from those that might be expected by the operation of chance alone; if rejected, it increases confidence in the h.. sequence h. that the amino acid sequence of a protein is determined by a particular sequence of nucleotides (the cistron) in the DNA of the organism producing the protein. sliding filament h. the theory that the contracting muscle shortens because two sets of filaments slide past each other. Starling h. the principle that net filtration through capillary membranes is proportional to the transmembrane hydrostatic pressure difference minus the transmembrane oncotic pressure difference; although well established, it is called Starling h. to distinguish it from Starling law of the heart. upregulation/downregulation h. a theory of the neurochemical basis of depression (an elaboration of the monoamine h.) linking it to an increase in number (upregulation) of postsynaptic monoamine receptors, which are then effectively decreased in number (downregulation) as a result of antidepressant activity. SEE ALSO: monoamine h.. wobble h. wobble base, wobble. zwitter h. that an amphoteric molecule ( e.g., an amino acid) has, at its isoelectric point, equal numbers of positive and negative charges, thus becoming a zwitterion.

hypothrombinemia (hi′po-throm-bin-e′me-a)
Abnormally small amounts of thrombin in the circulating blood, resulting in bleeding tendency.

hypothromboplastinemia (hi′po-throm′bo-plas-ti-ne′me-a)
Abnormally small amounts of thromboplastin in the blood, as a result of deficient quantities being released from the tissues.

hypothymia (hi′po-thi′me-a)
Depression of spirits; the “blues.” [hypo- + G. thymos, mind, soul]

hypothymic (hi-po-the′mik)
Denoting or characteristic of hypothymia.

hypothymism (hi′po-thi′mizm)
Obsolete term for inadequate function of the thymus.

hypothyroid (hi′po-thi′royd)
Marked by reduced thyroid function.

hypothyroidism (hi′po-thi′royd-izm)
Diminished production of thyroid hormone, leading to clinical manifestations of thyroid insufficiency, including low metabolic rate, tendency to weight gain, somnolence and sometimes myxedema. SYN: athyrea (1) . [hypo- + G. thyreoeides, thyroid] congenital h. lack of thyroid secretion. See infantile h.. infantile h. can be due to endemic congenital goiter, nonendemic cases are usually due to defective thyroidal embryogenesis, defective hypothalamic-pituitary function, congenital defects in thyroid hormone synthesis or action, or intrauterine exposure to goitrogenic agents. SYN: Brissaud infantilism, congenital myxedema, dysthyroidal infantilism, hypothyroid dwarfism, hypothyroid infantilism, infantile myxedema, myxedematous infantilism. secondary h. h. that arises as a consequence of inadequate thyrotropin secretion by the anterior pituitary gland.

hypothyroxinemia (hi′po-thi-rok-sin-e′me-a)
A subnormal thyroxine concentration in the blood.

hypotonia (hi′po-to′ne-a)
1. Reduced tension in any part, as in the eyeball. 2. Relaxation of the arteries. 3. A condition in which there is a diminution or loss of muscular tonicity. SYN: hypotonicity (1) , hypotonus, hypotony. [hypo- + G. tonos, tone] benign congenital h. nonprogressive h. of unknown etiology in infants and children; other known causes of hyptonia must be excluded.

hypotonic (hi-po-ton′ik)
1. Having a lesser degree of tension. 2. Having a lesser osmotic pressure than a reference solution, which is ordinarily assumed to be blood plasma or interstitial fluid; more specifically, refers to a fluid in which cells would swell. SYN: hypoisotonic.

hypotonicity (hi′po-to-nis′i-te)
1. SYN: hypotonia. 2. A decreased effective osmotic pressure.

hypotonus, hypotony (hi′po-to′nus, hi-pot′o-ne)
SYN: hypotonia.

hypotrichiasis (hi′po-tri-ki′a-sis)
1. SYN: hypotrichosis. 2. SYN: alopecia congenitalis. [hypo- + G. trichiasis, hairiness]

hypotrichosis (hi′po-tri-ko′sis)
A less than normal amount of hair on the head and/or body. SYN: hypotrichiasis (1) , oligotrichia, oligotrichosis. [hypo- + G. trichosis, hairiness]

hypotropia (hi-po-tro′pe-a)
An ocular deviation with one eye lower than the other. [hypo- + G. trope, turn]

hypotympanotomy (hi′po-tim-pa-not′o-me)
Operative procedure for the excision, without sacrifice of hearing, of small tumors confined to the lower portion of the tympanic cavity. [hypo- + G. tympanon, tympanum, + tome, incision]

hypotympanum (hi′po-tim′pa-num)
The lower part of the tympanic cavity. It is separated by a bony wall from the jugular bulb.

hypouresis (hi′po-u-re′sis)
Reduced flow of urine.

hypouricemia (hi′po-u-ri-se′me-a)
Reduced blood concentration of uric acid.

hypouricuria (hi′po-u′ri-ku′re-a)
Reduced excretion of uric acid in the urine. hereditary renal h. an autosomal recessive disorder caused by defective reabsorption of urate in the renal proximal tubule.

hypovarianism (hi′po-va′re-an-izm)
SYN: hypoovarianism.

hypoventilation (hi′po-ven-ti-la′shun)
Reduced alveolar ventilation relative to metabolic carbon dioxide production, so that alveolar carbon dioxide pressure increases above normal. SYN: underventilation.

hypovitaminosis (hi′po-vi′ta-min-o′sis)
A nutritional deficiency state characterized by relative insufficiency of one or more vitamins in the diet; manifested first by depletion of tissue levels, then by functional changes, and finally by appearance of morphologic lesions. Cf.:avitaminosis.


. . . Feedback