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تعداد آیتم قابل مشاهده باقیمانده : 3 مورد
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Laboratory testing for evaluating a neonate or young infant with suspected cholestatic liver disease

Laboratory testing for evaluating a neonate or young infant with suspected cholestatic liver disease
Finding Implications
Initial tests for all infants
Comprehensive metabolic panel
  • Total and conjugated bilirubin
 To evaluate for conjugated hyperbilirubinemia (cholestasis) versus unconjugated hyperbilirubinemia.
  • ALT and AST
 To assess for hepatocyte injury.
  • Alkaline phosphatase and GGTP
 To assess for biliary injury. Furthermore, several genetic/metabolic disorders can be divided into high- and low-GGTP categories.
  • Total protein and albumin
 To assess hepatocyte function. Low albumin suggests poor nutrition, renal losses, or poor hepatic synthetic function.
  • Electrolytes, bicarbonate, glucose
 To assess for metabolic disease. Abnormalities in these results are often seen in infants with metabolic disease.
CBC with differential To assess for infection and/or splenic sequestration. Elevated WBC is suggestive of infection. Low WBC and platelet count could indicate portal hypertension (with splenic sequestration).
PT/INR and PTT To assess hepatocyte function and/or vitamin K deficiency. Abnormal results indicate impaired liver synthetic function and/or vitamin K deficiency.
Additional tests to evaluate for systemic illness of specific liver diseasesΔ
Urinalysis and urine culture Appropriate for most infants with cholestasis to exclude urinary tract infection and to evaluate possible kidney involvement.
Blood culture If clinical presentation suggests sepsis.
Urine-reducing substances Screen for galactosemia (in infants ingesting lactose)◊.
Urine succinylacetone Screen for tyrosinemia.
Serum bile acids Elevations are diagnostic of cholestasis. Serum bile acids will be low in infants with bile acid synthetic disorders.
Alpha-1 antitrypsin concentration Low levels suggest alpha-1 antitrypsin deficiency. Normal levels do not exclude alpha-1 antitrypsin deficiency, because this is an acute phase reactant.
  • Protease inhibitor phenotype (PI type)
 The primary alleles associated with liver disease are PI*ZZ homozygosity or PI*SZ heterozygosity.
TSH, T4 Screen for congenital hypothyroidism (primary or central).
ACTH, cortisol Screen for adrenal insufficiency and hypopituitarism.
Serum ferritin, iron profile including iron, transferrin Elevations suggestive of gestational alloimmune liver disease and hemophagocytic lymphohistiocytosis.
Urine bile acid analysis by FAB-MS Screen for BASD, which may present with low-GGT cholestasis§.
Metabolic testing If a metabolic disorder is suspected, initial screening includes creatine kinase, plasma amino acids, urine organic acids, acylcarnitine profile, ammonia, lactate:pyruvate ratio.
Genetic testing Genetic testing is rapidly evolving with the availability of new technologies¥. It may include karyotype, targeted gene panels, and/or whole-exome sequencing.

ACTH: adrenocorticotropic hormone; ALT: alanine aminotransferase; AST: aspartate aminotransferase; BASD: bile acid synthetic defects; CBC: complete blood count; FAB-MS: fast atom bombardment mass spectrometry; GGT: gamma-glutamyl transferase; GGTP: gamma-glutamyl transpeptidase; INR: international normalized ratio; PT: prothrombin time; PTT: partial thromboplastin time; T4: thyroxine; TSH: thyroid-stimulating hormone (thyrotropin); WBC: white blood cell count.

¶ GGTP is disproportionately elevated (compared with AST and ALT) in the most common types of neonatal cholestasis, including biliary atresia and Alagille syndrome, while a normal or low GGTP is seen in most forms of progressive familial intrahepatic cholestasis, BASD, and arthrogryposis-renal dysfunction-cholestasis syndrome.

Δ These tests are selected based on the clinical presentation and results of initial tests.

◊ Urine-reducing substances is only valid as a screen for galactosemia if the infant is fed breast milk or a cow's milk-based formula (which contains lactose, then hydrolyzed to galactose).

§ Infants must be off of ursodeoxycholic acid for at least 5 days prior to urine collection for bile acid analysis because the FAB-MS signature of the drug overlaps with some of the abnormal bile acid metabolites seen in BASD.

¥ Individual gene sequencing can be done if the clinical presentation suggests a specific diagnosis, such as Alagille syndrome. For screening of multiple genes associated with inherited cholestasis, next-generation sequencing panels are available. Each panel interrogates approximately 20 to 70 genes. Current information is available at GeneTests.org.
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