JAUNDICE

Jaundice (icterus) is a yellow discoloration of the sclerae and skin as a result of a raised serum bilirubin. It is usually detectable clinically when the bilirubin exceeds 50 |imol/L (3 mg/dL).

Bilirubin is derived predominantly from the breakdown of haemoglobin in the spleen, and is carried in the blood bound to albumin. Unconjugated bilirubin is conjugated in the liver by glucuronyl transferase to bilirubin glu-curonide, and this is excreted via the bile duct into the small intestine in bile. In the terminal ileum conjugated bilirubin is converted to urobilinogen and excreted in the faeces (as stercobilinogen, responsible for the pigmentation of faeces) or reabsorbed and excreted by the kidneys (Fig. 4.2).

For clinical and diagnostic purposes three major categories of jaundice can be considered:

■ Haemolytic jaundice

■ Congenital hyperbilirubinaemias - impaired conjugation of bilirubin or bilirubin handling by the liver. Liver biochemistry is normal other than raised bilirubin.

■ Cholestatic jaundice - failure of bile secretion by the liver or bile duct obstruction. Liver biochemistry is abnormal.

Haemolytic jaundice

Increased breakdown of red blood cells leads to increased production of bilirubin, which usually results in mild jaundice only (68-102 |imol/L or 4 -6 mg/dL), as the liver can usually handle the increased bilirubin derived from haemolysis. The unconjugated bilirubin is not water soluble and there-fore does not pass into the urine, unlike the conjugated hyperbilirubinaemia of cholestatic jaundice. Urinary urobilinogen is increased. The causes are those of haemolytic anaemia (p. 206), with the clinical features dependent on the cause. Investigations show features of haemolysis (p. 207), with raised serum unconjugated bilirubin and otherwise normal liver biochemistry.

Congenital hyperbilirubinaemia

The most common congenital hyperbilirubinaemia is Gilbert's syndrome, which affects 2-7% of the population. It is asymptomatic and is usually picked up as an incidental finding of a slightly raised serum bilirubin (17102 |imol/L, 1-6 mg/dL). Mutations in the gene coding for UDP-glucuronyl transferase lead to reduced enzyme activity and reduced conjugation of

Pathways in bilirubin metabolism

Fig. 4.2 Pathways in bilirubin metabolism.

bilirubin with glucuronic acid. Diagnosis is based on the findings of uncon-jugated hyperbilirubinaemia with otherwise normal liver biochemistry, normal full blood count, smear and reticulocyte count (thus excluding haemolysis) and absence of signs of liver disease. The patient should be reassured that no further investigation or treatment is necessary.

Other congenital abnormalities of bilirubin metabolism (Crigler-Najjar, Dubin-Johnson and Rotor's syndromes, benign recurrent intrahepatic cholestasis) are rare.

Cholestatic jaundice

This can be divided into the following (Fig. 4.3):

■ Intrahepatic cholestasis, caused by hepatocellular swelling in parenchy-mal liver disease or abnormalities at a cellular level of bile excretion

■ Extrahepatic cholestasis resulting from obstruction of bile flow at any point distal to the bile canaliculi.

In both types there is jaundice with pale stools and dark urine and the bilirubin is conjugated.

Causes of jaundice

Fig. 4.3 Causes of jaundice.

However, intrahepatic and extrahepatic choleslatic jaundice must be dif-ferentiated as their management is quite different.

Investigations

An outline of the approach to the investigation of jaundice is shown in Fig. 4.4.

■ Serum liver biochemistry will confirm the jaundice. The AST tends to be high early in the course of hepatitis, with a smaller rise in alkaline phos-phatase. Conversely, in extrahepatic obstruction the alkaline phosphatase is elevated, with a smaller rise in the AST.

■ US examination shows dilated bile ducts in extrahepatic cholestasis and may identify the level of obstruction and the cause e.g. gallstones, tumours.

■ Serum viral markers for hepatitis A or hepatitis B are present in acute viral hepatitis. Antibodies to hepatitis C virus develop late in the course of acute infection but HCV RNA is usually detectable by 1-2 weeks.

■ Other tests - prothrombin time may be prolonged as a result of vitamin K malabsorption and is corrected by administration of vitamin K (p. 242). Serum autoantibodies are present in autoimmune liver disease (see later).

Approach to the investigation of cholestatic jaundice

ERCP = endoscopic retrograde cholangiopancreatography

MRCP = magnetic resonance cholangiopancreatography

PTC = percutaneous transhepatic cholangiogram

Fig. 4.4 Approach to the investigation of cholestatic jaundice. The order of investigation is influenced by the age of the patient and hence the likely cause of jaundice. A young person is most likely to have intrinsic liver disease, e.g. viral hepatitis, and it may be more appropriate to organize tests to exclude these conditions before proceeding to US. See page 150 for clinical features.

Ebook Essentials of Kumar and Clark's Clinical Medicine, 5e

1. Ethics and communication

Ethics and communication

2. Infectious diseases

Infectious diseases

3. Gastroenterology and nutrition

Gastroenterology and nutrition

4. Liver, biliary tract and pancreatic disease

Liver, biliary tract and pancreatic disease
LIVER BIOCHEMISTRY AND LIVER FUNCTION TESTS
SYMPTOMS AND SIGNS OF LIVER DISEASE
JAUNDICE
HEPATITIS
NON - ALCOHOLIC FATTY LIVER DISEASE (NAFLD)
CIRRHOSIS
COMPLICATIONS AND EFFECTS OF CIRRHOSIS
LIVER TRANSPLANTATION
TYPES OF CHRONIC LIVER DISEASE AND CIRRHOSIS
PRIMARY SCLEROSING CHOLANGITIS
BUDD - CHIARI SYNDROME
LIVER ABSCESS
LIVER DISEASE IN PREGNANCY
LIVER TUMOURS
GALLSTONES
THE PANCREAS
CARCINOMA OF THE PANCREAS
NEUROENDOCRINE TUMOURS OF THE PANCREAS

5. Haematological disease

Haematological disease
ANAEMIA
Assessment and treatment of suspected neutropenic sepsis
HAEMOLYTIC ANAEMIA
INHERITED HAEMOLYTIC ANAEMIAS
ACQUIRED HAEMOLYTIC ANAEMIA
MYELOPROLIFERATIVE DISORDERS
THE SPLEEN
BLOOD TRANSFUSION
THE WHITE CELL
HAEMOSTASIS AND THROMBOSIS
THROMBOSIS
THERAPEUTICS

6. Malignant disease

Malignant disease
MYELOABLATIVE THERAPY AND HAEMOPOIETIC STEM CELL TRANSPLANTATION
THE LYMPHOMAS
THE PARAPROTEINAEMIAS
PALLIATIVE MEDICINE AND SYMPTOM CONTROL

7. Rheumatology

Rheumatology
COMMON INVESTIGATIONS IN MUSCULOSKELETAL DISEASE
COMMON REGIONAL MUSCULOSKELETAL PROBLEMS
BACK PAIN
OSTEOARTHRITIS
INFLAMMATORY ARTHRITIS
THE SERONEGATIVE SPONDYLOARTHROPATHIES
Clinical features, Investigations
INFECTION OF JOINTS AND BONES
AUTOIMMUNE RHEUMATIC DISEASES
SYSTEMIC INFLAMMATORY VASCULITIS
DISEASES OF BONE
THERAPEUTICS

8. Water, electrolytes and acid–base balance

WATER AND ELECTROLYTE REQUIREMENTS
BODY FLUID COMPARTMENTS
REGULATION OF BODY FLUID HOMEOSTASIS
PLASMA OSMOLALITY AND DISORDERS OF SODIUM REGULATION
DISORDERS OF POTASSIUM REGULATION
DISORDERS OF MAGNESIUM REGULATION
DISORDERS OF ACID - BASE BALANCE
THERAPEUTICS

9. Renal disease

Renal disease
INVESTIGATION OF RENAL DISEASE
GLOMERULAR DISEASES
NEPHROTIC SYNDROME
URINARY TRACT INFECTION
TUBULOINTERSTITIAL NEPHRITIS
HYPERTENSION AND THE KIDNEY
RENAL CALCULI AND NEPHROCALCINOSIS
URINARY TRACT OBSTRUCTION
ACUTE RENAL FAILURE/ACUTE KIDNEY INJURY
CHRONIC KIDNEY DISEASE
RENAL REPLACEMENT THERAPY
CYSTIC RENAL DISEASE
TUMOURS OF THE KIDNEY AND GENITOURINARY TRACT
DISEASES OF THE PROSTATE GLAND
TESTICULAR TUMOUR
URINARY INCONTINENCE

10. Cardiovascular disease

COMMON PRESENTING SYMPTOMS OF HEART DISEASE
INVESTIGATIONS IN CARDIAC DISEASE
CARDIAC ARRHYTHMIAS
HEART FAILURE
ISCHAEMIC HEART DISEASE
RHEUMATIC FEVER
VALVULAR HEART DISEASE
PULMONARY HEART DISEASE
MYOCARDIAL DISEASE
CARDIOMYOPATHY
PERICARDIAL DISEASE
SYSTEMIC HYPERTENSION
ARTERIAL AND VENOUS DISEASE
ELECTRICAL CARDIOVERSION
DRUGS FOR ARRHYTHMIAS
DRUGS FOR HEART FAILURE
DRUGS AFFECTING THE RENIN - ANGIOTENSIN SYSTEM
NITRATES, CALCIUM - CHANNEL BLOCKERS AND POTASSIUM - CHANNEL ACTIVATORS

11. Respiratory disease


Respiratory disease
TUBERCULOSISnd
DIFFUSE DISEASES OF THE LUNG PARENCHYMA
OCCUPATIONAL LUNG DISEASE
CARCINOMA OF THE LUNG
DISEASES OF THE CHEST WALL AND PLEURA
DISORDERS OF THE DIAPHRAGM

12. Intensive care medicine

Intensive care medicine

13. Drug therapy, poisoning, and alcohol misuse

Drug therapy, poisoning, and alcohol misuse

14. Endocrine disease

Endocrine disease
PITUITARY HYPERSECRETION SYNDROMES
THE THYROID AXIS
MALE REPRODUCTION AND SEX
FEMALE REPRODUCTION AND SEX
THE GLUCOCORTICOID AXIS
THE THIRST AXIS
DISORDERS OF CALCIUM METABOLISM
DISORDERS OF PHOSPHATE CONCENTRATION
ENDOCRINOLOGY OF BLOOD PRESSURE CONTROL
DISORDERS OF TEMPERATURE REGULATION
THERAPEUTICS

15. Diabetes mellitus and other disorders of metabolism

DIABETES MELLITUS
DIABETIC METABOLIC EMERGENCIES
COMPLICATIONS OF DIABETES
SPECIAL SITUATIONS
HYPOGLYCAEMIA IN THE NON - DIABETIC
DISORDERS OF LIPID METABOLISM
THE PORPHYRIAS

16. The special senses

THE EAR
THE NOSE AND NASAL CAVITY
THE THROAT
THE EYE

17. Neurology

COMMON NEUROLOGICAL SYMPTOMS
COORDINATION OF MOVEMENT
THE CRANIAL NERVES
COMMON INVESTIGATIONS IN NEUROLOGICAL DISEASE
UNCONSCIOUSNESS AND COMA
STROKE AND CEREBROVASCULAR DISEASE
EPILEPSY AND LOSS OF CONSCIOUSNESS
NERVOUS SYSTEM INFECTION AND INFLAMMATION
HYDROCEPHALUS
HEADACHE, MIGRAINE AND FACIAL PAIN
SPINAL CORD DISEASE
DEGENERATIVE NEURONAL DISEASES
DISEASES OF THE PERIPHERAL NERVES
MUSCLE DISEASES
MYOTONIAS
DELIRIUM
THERAPEUTICS

18. Dermatology

Dermatology

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