出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/07/09 21:06:21」(JST)
| Neonatal jaundice | |
|---|---|
| Jaundice in newborn | |
| Classification and external resources | |
| Specialty | Pediatrics |
| ICD-10 | P58, P59 |
| ICD-9-CM | 773, 774 |
| DiseasesDB | 8881 |
| MedlinePlus | 001559 |
| eMedicine | ped/1061 |
| Patient UK | Neonatal jaundice |
| MeSH | D007567 |
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[edit on Wikidata]
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Neonatal jaundice or neonatal hyperbilirubinemia, or neonatal icterus (from the Greek word ἴκτερος), attributive adjective: icteric, is a yellowing of the skin and other tissues of a newborn infant. A bilirubin level of more than 85 μmol/l (5 mg/dL) leads to a jaundiced appearance in neonates whereas in adults a level of 34 μmol/l (2 mg/dL) is needed for this to occur. In newborns, jaundice is detected by blanching the skin with pressure applied by a finger so that it reveals underlying skin and subcutaneous tissue.[1] Jaundiced newborns have yellow discoloration of the white part of the eye, and yellowing of the face, extending down onto the chest.
Neonatal jaundice can make the newborn sleepy and interfere with feeding. Extreme jaundice can cause permanent brain damage from kernicterus.
In neonates, the yellow discoloration of the skin is first noted in the face and as the bilirubin level rises proceeds caudal to the trunk and then to the extremities.[2] This condition is common in newborns affecting over half (50–60%) of all babies in the first week of life.[3]
Infants whose palms and soles are yellow, have serum bilirubin level over 255 μmol/l (15 mg/dL) (more serious level). Studies have shown that trained examiners assessment of levels of jaundice show moderate agreement with icterometer bilirubin measurements.[2] In infants, jaundice can be measured using invasive or non-invasive methods.
In neonates, jaundice tends to develop because of two factors—the breakdown of fetal hemoglobin as it is replaced with adult hemoglobin and the relatively immature metabolic pathways of the liver, which are unable to conjugate and so excrete bilirubin as quickly as an adult. This causes an accumulation of bilirubin in the blood (hyperbilirubinemia), leading to the symptoms of jaundice.
If the neonatal jaundice does not clear up with simple phototherapy, other causes such as biliary atresia, Progressive familial intrahepatic cholestasis, bile duct paucity, Alagille syndrome, alpha 1-antitrypsin deficiency, and other pediatric liver diseases should be considered. The evaluation for these will include blood work and a variety of diagnostic tests. Prolonged neonatal jaundice is serious and should be followed up promptly.
Severe neonatal jaundice may indicate the presence of other conditions contributing to the elevated bilirubin levels, of which there are a large variety of possibilities (see below). These should be detected or excluded as part of the differential diagnosis to prevent the development of complications. They can be grouped into the following categories:
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Neonatal jaundice |
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Unconjugated bilirubin |
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Conjugated bilirubin | ||||||||||||||||||||||||||||||||
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Pathologic |
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Physiological jaundice of Neonates |
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Hepatic |
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Post-hepatic |
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Hemolytic |
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Non-hemolytic |
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Intrinsic causes |
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Extrinsic causes |
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"Breastfeeding jaundice" or "lack of breastfeeding jaundice," is caused by insufficient breast milk intake,[4] resulting in inadequate quantities of bowel movements to remove bilirubin from the body. This leads to increased enterohepatic circulation, resulting in increased reabsorption of bilirubin from the intestines.[5] Usually occurring in the first week of life, most cases can be ameliorated by frequent breastfeeding sessions of sufficient duration to stimulate adequate milk production.
Whereas breastfeeding jaundice is a mechanical problem, breast milk jaundice is a biochemical occurrence and the higher bilirubin possibly acts as an antioxidant. Breast milk jaundice occurs later in the newborn period, with the bilirubin level usually peaking in the sixth to 14th days of life. This late-onset jaundice may develop in up to one third of healthy breastfed infants.[6]
Most infants develop visible jaundice due to elevation of unconjugated bilirubin concentration during their first week. This common condition is called physiological jaundice. This pattern of hyperbilirubinemia has been classified into two functionally distinct periods.
Mechanism involved in physiological jaundice are mainly:
Clinical Assessment
This method is less accurate and more subjective in estimating jaundice.
Ingram icterometer: In this method a piece of transparent plastic known as Ingram icterometer is used. Ingram icterometer is painted in five transverse strips of graded yellow lines. The instrument is pressed against the nose and the yellow colour of the blanched skin is matched with the graded yellow lines and bilirubin level is assigned.
Transcutaneous bilirubinometer: This is hand held, portable and rechargeable but expensive and sophisticated. When pressure is applied to the photoprobe, a xenon tube generates a strobe light, and this light passes through the subcutaneous tissue. The reflected light returns through the second fiber optic bundle to the spectrophotometric module. The intensity of the yellow color in this light, after correcting for the hemoglobin, is measured and instantly displayed in arbitrary units.
Any of the following features characterizes pathological jaundice:
The aim of clinical assessment is to distinguish physiological from pathological jaundice. The signs which help to differentiate pathological jaundice of neonates from physiological jaundice of neonates are the presence of intrauterine growth restriction, stigma of intrauterine infections (e.g. cataracts, small head, and enlargement of the liver and spleen), cephalohematoma, bruising, signs of bleeding in the brain's ventricles. History of illness is noteworthy. Family history of jaundice and anemia, family history of neonatal or early infant death due to liver disease, maternal illness suggestive of viral infection (fever, rash or lymphadenopathy), maternal drugs (e.g. sulphonamides, anti-malarials causing red blood cell destruction in G6PD deficiency) are suggestive of pathological jaundice in neonates.[14]
The bilirubin levels for initiative of phototherapy varies depends on the age and health status of the newborn. However, any newborn with a total serum bilirubin greater than 359 μmol/l ( 21 mg/dL) should receive phototherapy.[15]
Phenobarbital is used to treat neonatal jaundice by increasing liver metabolism and thus lowering bilirubin levels. In the 1950s, phototherapy was discovered, and became the standard treatment, however phenobarbital therapy is still in common use when access to phototherapy is inconvenient or impractical. One striking benefit of successful phenobarbital therapy is the rapid onset of recovery.[16]
The use of phototherapy was first discovered, accidentally, at Rochford Hospital in Essex, England. The ward sister (nurse) of the premature baby unit firmly believed that the infants under her care benefited from fresh air and sunlight in the courtyard. Although this led to the first noticing of jaundice being improved with sunlight, further studies only progressed when a vial of blood sent for bilirubin measurement sat on a windowsill in the lab for several hours. The results indicated a much lower level of bilirubin than expected based on the patient's visible jaundice. Further investigation led to the determination that blue light, wavelength of 420-480 nm (peak 458 nm), caused transformation of the trans bilirubin to cis bilirubin, a soluble product that does not contribute to kernicterus. Although some pediatricians began using phototherapy in the United Kingdom following Dr. Cremer's publishing the above facts in the Lancet in 1958, most hospitals only began to regularly use phototherapy ten years later when an American group independently made the same discovery.[17][18]
Infants with neonatal jaundice are treated with colored light called phototherapy. Physicians randomly assigned 66 infants 35 weeks of gestation to receive phototherapy. After 15±5 the levels of bilirubin, a yellowish bile pigment that in excessive amounts causes jaundice, were decreased down to 0.27±0.25 mg/dl/h in the blue light. This suggests that blue light therapy helps reduce high bilirubin levels that cause neonatal jaundice.[19]
Exposing infants to high levels of colored light changes trans-bilirubin to the more water-soluble cis-form which is excreted in the bile. Scientists studied 616 capillary blood samples from jaundiced newborn infants. These samples were randomly divided into three groups. One group contained 133 samples and would receive phototherapy with blue light. Another group contained 202 samples would receive room light, or white light. The final group contained 215 samples, and were left in a dark room. The total bilirubin levels were checked at 0, 2, 4, 6, 24, and 48 hours. There was a significant decrease in bilirubin in the first group exposed to phototherapy after two hours, but no change occurred in the white light and dark room group. After 6 hours, there was a significant change in bilirubin level in the white light group but not the dark room group. It took 48 hours to record a change in the dark room group’s bilirubin level. Phototherapy is the most effective way of breaking down a neonate’s bilirubin.[20]
Phototherapy works through a process of isomerization that changes trans-bilirubin into the water-soluble cis-bilirubin isomer.[21][22]
In phototherapy, blue light is typically used because it is more effective at breaking down bilirubin (Amato, Inaebnit, 1991). Two matched groups of newborn infants with jaundice were exposed to intensive green or blue light phototherapy. The efficiency of the treatment was measured by the rate of decline of serum bilirubin, which in excessive amounts causes jaundice, concentration after 6, 12 and 24 hours of light exposure. A more rapid response was obtained using the blue lamps than the green lamps. However, a shorter phototherapy recovery period was noticed in babies exposed to the green lamps(1). Green light is not commonly used because exposure time must be longer to see dramatic results.
The phototherapy involved is not ultraviolet light therapy but rather a specific frequency of blue light. Where ultraviolet light therapy in childhood may increase the risk of skin moles, and is often associated with an increased risk of skin cancer[23][24][25], the specific frequency used in this phototherapy does not carry those risks.
Increased feedings help move bilirubin through the neonate’s metabolic system.[26]
The light can be applied with overhead lamps, which means that the baby's eyes need to be covered, or with a device called a Biliblanket, which sits under the baby's clothing close to its skin.
Much like with phototherapy the level at which exchange transfusion should occur depends on the health status and age of the newborn. It should however be used for any newborn with a total serum bilirubin of greater than 428 μmol/l ( 25 mg/dL ).[15]
Prolonged hyperbilirubinemia (severe jaundice) can result in chronic bilirubin encephalopathy (kernicterus).[27][28] Quick and accurate treatment of neonatal jaundice helps to reduce the risk of neonates developing kernicterus.[29]
Infants with kernicterus may have a fever[30] or seizures.[31] High pitched crying is an effect of kernicterus. Scientists used a computer to record and measure cranial nerves 8, 9 and 12 in 50 infants who were divided into two groups equally depending upon bilirubin concentrations. Of the 50 infants, 43 had tracings of high pitched crying.[32]
Exchange transfusions performed to lower high bilirubin levels are an aggressive treatment.[33]
American Academy of Pediatrics has issued guidelines for managing this disease, which can be obtained for free.[34]
National Institute for Health and Care Excellence (NICE) has issued guidelines for the recognition and treatment of neonatal jaundice in the United Kingdom.[35]
Certain conditions originating in the perinatal period / fetal disease (P, 760–779)
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| Maternal factors and complications of pregnancy, |
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| Length of gestation and fetal growth |
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| Birth trauma |
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| リンク元 | 「母乳性黄疸」 |
| 関連記事 | 「mi」「breast」「jaundiced」「jaundice」「milk」 |