Lipemia

LIPEMIA, literally - the content of fat in the blood, but usually the word L. denotes an increase in the amount of fat in the blood (although the latter would be more accurately called hyperlipemia). In hyperlipemia the serum and plasma appear turbid, and sometimes acquire a milky appearance with a faint yellowish tint (sanguis lacteus). The whole blood acquires in these cases a light-brownish tone (with a purple tint in places where the separation of serum is noticeable). If a fresh drop of lipemic blood is viewed under a microscope (and even better in an ultramicroscope), one can see a mass of tiny particles in lively oscillatory motion; these will be fat droplets, the so-called hemokonia. All these properties the serum or plasma acquires in the case if the amount of fat in it, which is normally fasting at 0.1-0.5%, exceeds 1%; it can reach 20% and even more. However, strong L. is not always noticeable to the eye: there exists hidden L. with clear serum. This is especially the case with diseases of the liver due to the retention in the blood of bile acids, some of which possess the ability to convert fat into a dissolved state (see Bile). Upon standing such plasma may become turbid. Neutral fat is contained almost exclusively in the plasma, not in the red corpuscles. The fat content fasting is the same in venous and arterial blood. Under physiological conditions hyperlipemia is observed first of all during the period of digestion (serum chylosum). After the intake of oil L. increases already after an hour, reaches a maximum after 6 hours, and ceases after 8-10 hours. Repeated administration of oil does not necessarily strengthen hyperlipemia, and large doses can cause hyperlipemia no greater than that given by a load with a small amount of oil. Dietary L. occurs in omnivores and carnivores, while in herbivores (in which fat is absorbed slowly due to low secretion of bile acids) it is very weakly expressed. Secondly, L. slightly increases during pregnancy. Thirdly, strong fasting or exhaustion also causes an increase in the fat content in the blood. Among diseases in which hyperlipemia occurs, diabetes should be noted first of all. However, its frequency in this disease is somewhat exaggerated (and the milky appearance of serum is even rare). The degree of L. in this case is not related to a fat-rich diet, nor to exhaustion. In severe forms, especially with acidosis, L. is significant. However, there is no complete parallelism between the fat content in the blood and ketonuria or glycosuria. Fat in the blood decreases under the influence of insulin treatment. Furthermore, fat in the blood is often increased in acute and chronic diffuse diseases of the liver and hepatic jaundices (this is all the more interesting because in this case dietary fat is very poorly absorbed). Hyperlipemia is also noted in Bright's disease, mainly in nephrosis. The L. after phlebotomy or bleeding is well known, both in experiment and in humans; the latter occurs mainly with significant and acute hemorrhages. In this case fat can increase in the blood twentyfold. Fat in the blood can also increase strongly in severe anemias of other origin. L. also arises in connection with various poisons both in experiment (pyridine, phenylhydrazine, etc.) and in humans (chloroform anesthesia, alcohol); it reaches a huge degree in phosphorus poisoning. Lipemia has also been described in pancreatitis. It should be noted that a systematic study of blood fat in various diseases is absent, and so far we have only isolated facts in this regard, which can only be explained hypothetically. Two types of L. are distinguished: "transport" and "retention" L. The first depends on the transfer of fat from the digestive organs to fat depots (an example of this is dietary L.) or from fat depots to certain cells or tissues: this apparently occurs in pathological obesity of internal organs (e.g., degenerative diseases of the liver, kidneys, severe anemia, poisons, etc.); this also includes L. after phlebotomy, depending on the mobilization of tissue fat together with tissue juices; a vivid example of this type is L. of fasting people, which arises only when there are still fat depots in the body, and ceases immediately as soon as they are exhausted. The second type of L. is explained by a peculiar retention of fat in the blood: fat as if loses the ability to be deposited or consumed; an example can be L. in diabetes, in which, as is known, in addition to carbohydrate metabolism, fat metabolism can also be disturbed; it is characteristic that under these conditions the dietary supply of fat has almost no effect on the amount of fat in the blood. L. should be distinguished from lipoidemia; the first concerns the content of neutral fat in the blood, the second - phosphatides (lecithin) and sterols (cholesterol). Often the fat content in the blood fluctuates in parallel with the lipoid content; but in some conditions there is a quantitative discrepancy between fat and blood lipoids. As for the ratio of the lipoids themselves in the blood, regarding cholesterol ^; see Hypercholesterolemia, hypocholesterolemia, and the rest have been studied, but still very insufficiently, lecithin. The content of lecithin in the blood changes under various physiological and pathological conditions approximately as cholesterol does. Deviations in the quantitative ratio ^X^fjy^p-» ⁱⁿ the generally quite constant create (or rather reflect) important changes in biochemical and colloidal processes occurring in the organism. With intensified intake into the body (in the form of acute loading) of neutral fat, not only L., but also the mass of blood lipoids increases, and with a load, for example, of cholesterol, not only the amount of cholesterol, but also lecithin and neutral fat increase in the blood. Lit.: Bang I., Chemie und Biochemie der Li-poide, Wiesbaden, 1911; B 1 o o г W., On fat absorption, Journ. of biol. chem., v. XI, 1912; Burger M., t!ber cholumische Lipamie, Munch, med. Wochen-schrift, 1922, № 4; E d e 1 m a n n F., t)ber Ursache und Entstehung der Aderlasslipamie, Ztschr. f. d. ges. experim. Med., B. XXX, 1922; Feigi J., Uber das Vorkommen von Fetten und Lipoiden im menschlichen Blutplasma, Biocbom. Ztschr., B. XC, 1918; G r i-« a u t A. et Yovanovitch B,., L 'equilibre li-jpoidique du serum sanguin, Comptes rendus de la So-ciete de biologie, v. XCI, 1924; Joel E., tfber spon-tane und experimentelle Lipamien, Klin. Wochenschr., 1924, № 43; S a k a i S., Uber Pathogenese der Lipamie, Bioch. Ztschr., B. LXII, 1914; S c h o n h e i-m e r R., Ober. die Resorptionsbeschleunigung des Oholesterins bei Anwesenbeit von Desoxycholsaure, Bioch. Ztschr., B. CXVII, 1924; Widal F., Weil A. et Laudat M., La lipemie des brightiques, Semaine med., 1912, p. 529.