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NUTRITIONAL AND METABOLIC DISEASES

 
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Malnutrition Pseudogout Disorders of Amino-Acid Transport and Metabolism Haemochromatosis
Disturbances of Amino-Acid Transport Wilson's Disease Cystinuria Osteomalacia
Hartnup Disease Cystic Fibrosis Disturbances of Amino-Acid Metabolism Disorders of Porphyrin Metabolism
Phenylketonuria Erythropoietic Porphyrias Histidinemia Congenital Erythropoietic Porphyria
Homocystinuria Erythropoietic Protoporphyria Disorders of Carbohydrate Metabolism Hepatic Porphyrias
Von Gierke's Disease Acute Intermittent Porphyria Galactosemia Variegate Porphyria
Lactase Deficiency Hereditary Coproporphyria Disorders of Lipid Metabolism Porphyria Cutanea Tarda
Hypercholesterolemia Amyloidosis Endogenous Hypertriglyceridemia Disorders of Bilirubin Excretion
Hyperchlyomicronemia Unconjugated Hyperbilirubinemias Dysbetalipoproteinemia Gilbert's Syndrome
Mixed Hyperlipidemia Crigler-Najjar Syndrome Gout Conjugated Hyperbilirubinemias
Dubin-Johnson Syndrome Rotor's Syndrome .
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MALNUTRITION
LABORATORY FINDINGS
 
  • Decreased plasma albumin (<3.4 g/dl) and total protein - correlates with the degree of fatty liver and oedema
  • Decreased total iron binding capacity (<240 mcg/dl) - total iron binding capacity reflects transferrin concentration, which is a sensitive and early indicator of protein deficiency
  • Decreased 24-hr urine creatinine - this should be compared with the expected creatinine excretion based on the patient's height and sex
  • Decreased total lymphocyte count (<1500/ul)
  • Decreased blood urea nitrogen (BUN), magnesium, and urine urea nitrogen
  • Normocytic, normochromic anaemia - chronic disease type
  • Laboratory findings of impaired intestinal absorption and osteomalacia



DISORDERS OF AMINO-ACID TRANSPORT AND METABOLISM

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DISTURBANCES OF AMINO-ACID TRANSPORT

Cystinuria

Click on image for link to original page

LABORATORY FINDINGS

  • Presence of cystine crystals in the urine
  • Positive cyanide-nitroprusside test on urine and on calculi indicates presence of cystine.
  • Amino-acid analysis of urine shows increased excretion of cystine (20 - 30 times normal), lysine, arginine, and ornithine.
  • Haematuria occurs as a result of cystine calculi.

What is cystinuria?

Cystinuria is an inherited (genetic) disorder of the transport of an amino acid (a building block of protein) called cystine resulting in cystinuria (an excess of cystine in the urine) and the formation of cystine stones.

How frequent is cystinuria?

Cystinuria is one of the more common genetic disorders. Its overall prevalence is about 1 in 7,000 in the population.

Cystinuria is the most common defect known in the transport of an amino acid.

What is a transport defect?

Within the body, many molecules are able to pass across the membranes that surround cells. These molecules can accomplish this feat due to specific transport systems. These systems include special receptors on the membrane of the cell and special carrier proteins. The receptor recognizes the molecule and receives it on the cell membrane. Then the molecule hitches a ride through the cell membrane on the back of a carrier protein.

With such remarkable specificity, it is little wonder that sometimes there are defects in transport systems. Several dozen different diseases are now known to be due to transport defects.

What causes cystinuria?

Cystinuria is caused by the defective transport of cystine and several other amino acids through the cells of the kidney and the intestinal tract.

What happens with cystine in the urine?

Although cystine is not the only overly excreted amino acid in cystinuria, it is the least soluble of all naturally occurring amino acids. Cystine precipitates, or crystallizes out of urine and forms stones (calculi) in the kidney, ureter, bladder, or anywhere in the urinary tract.

The cystine stones (below) compared in size to a quarter (a U.S. $0.25 coin) were obtained from the kidney of a young woman by percutaneous nephrolithotripsy (PNL), a procedure for crushing and removing the dense stubborn stones characteristic of cystinuria.
Extracted from Focus on Womens Health Webpage

Hartnup Disease

LABORATORY FINDINGS
 

DISTURBANCES OF AMINO-ACID METABOLISM

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Phenylketonuria

PAH-catalysed reaction PHENYLKETONURIA (PKU) is an inherited error of metabolism caused by a deficiency in the enzyme phenylalanine hydroxylase. Loss of this enzyme results in mental retardation, organ damage, unusual posture and can, in cases of maternal PKU, severely compromise pregnancy.
  Classical PKU is an autosomal recessive disorder, caused by mutations in both alleles of the gene for phenylalanine hydroxylase (PAH), found on chromosome 12. In the body, phenylalanine hydroxylase converts the amino acid phenylalanine to tyrosine, another amino acid. Mutations in both copies of the gene for PAH means that the enzyme is inactive or is less efficient, and the concentration of phenylalanine in the body can build up to toxic levels. In some cases, mutations in PAH will result in a phenotypically mild form of PKU called hyperphenylalanemia. Both diseases are the result of a variety of mutations in the PAH locus; in those cases where a patient is heterozygous for two mutations of PAH (ie each copy of the gene has a different mutation), the milder mutation will predominate.
  A form of PKU has been discovered in mice, and these model organisms are helping us to better understand the disease, and find treatments against it. With careful dietary supervision, children born with PKU can lead normal lives, and mothers who have the disease can produce healthy children.
Extracted from NCBI page

LABORATORY FINDINGS

Histidinemia

LABORATORY FINDINGS

Homocystinuria

LABORATORY FINDINGS



DISORDERS OF CARBOHYDRATE METABOLISM

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Click on image for link to paper
on carbohydrate Metabolism


Click on image for link to original image at Tulane Uni.

VON GIERKE'S DISEASE

LABORATORY FINDINGS

  • Marked decrease in blood glucose due to impaired hepatic release of glucose
  • Increased lactic acid, marked
  • Decreased bicarbonate and pH (metabolic acidosis) due to increased lactic acid
  • Marked increase in triglycerides and cholesterol due to impaired lipid metabolism
  • Increased serum uric acid due to decreased urinary excretion of uric acid
  • Mild anaemia
  • Decreased serum phosphorus
  • Evidence of impaired platelet function - prlonged bleeding time, decreased platelet adhesion, and defective platelet aggregation
  • Liver biopsy shows increased glycogen and diminished glucose-6-phosphatase.

GALACTOSEMIA

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Galactosemia is an elevation of blood galactose levels. It may be due to a deficiency of any of the three enzymes of the galactose catabolic pathway: galactose-1-phosphate uridyltransferase (Gal-1-PUT), galactokinase, or UDP-galactose-4-epimerase. Clinically, deficiency of galactose-1-phosphate uridyltransferase (Gal-1-PUT) has become synonymous with classic galactosemia. This autosomal recessive disorder occurs with an incidence of approximately 1:40-60,000 in the general population. The symptoms can be severe in infancy and may lead to death or severe neurologic damage if not recognized and treated.

The description below is extracted from this web page: Newborn Screening Practitioner's Manual

Galactose is a monosaccharide present in many polysaccharides. Clinically, the most important source is the disaccharide lactose. Lactose is the predominant carbohydrate in human and most other animal milk, including cow's milk. Many commercially available infant formulas contain lactose. However, other formulas, such as some soy-based formulas, do not contain lactose. This is critical information to assess in patients as ingestion of galactose is prerequisite to the development of clinical symptoms.

Clinical Features

Galactose-1-phosphate uridyltransferase deficiency (Gal-1-PUT)

Galactosemia, due to a complete lack of Gal-1-PUT activity, presents in the first weeks of life. The most prominent clinical features are liver dysfunction manifest as jaundice and hypoglycemia; neurologic findings of irritability and seizures; and gastrointestinal findings of poor feeding, vomiting, and diarrhea. Other findings include cataracts and renal Fanconi's syndrome. Escherichia coli sepsis has been described in many patients with galactosemia. If the diagnosis of galactosemia is not made in the neonatal period, failure to thrive, chronic vomiting, hepatic cirrhosis, and mental retardation may develop in infants who survive. The diagnosis can be suspected clinically by the presence of the above symptoms, but some affected infants may be asymptomatic at the time of screening. Positive non-glucose urine reducing substances increases suspicion of the condition, but not all affected newborns will have a positive urine test.

There are several clinical variants due to genetic mutations in Gal-1-PUT that alter, but do not eliminate, enzyme activity. The most common of these are the Duarte and Los Angeles variants. Patients with these variants are usually clinically asymptomatic; however the reduced enzyme activity will be detected by newborn screening. Further testing is required.

Galactokinase deficiency

This is a rare defect manifest only by the development of cataracts, usually in the neonatal period, but occasionally delayed until adulthood. The toxic symptoms of Gal-1-PUT deficiency are not present, however the urine may be positive for reducing substances. Consideration of galactokinase deficiency should be given in any patient with an abnormal total galactose result and a normal Gal-1-PUT on the newborn screen.

UDP-galactose-4-epimerase deficiency

This is a very rare cause of galactosemia that may be either symptomatic or asymptomatic. Consideration should be given in any patient with an abnormal total galactose result and a normal Gal-1-PUT on the newborn screen.

LABORATORY FINDINGS


LACTASE DEFICIENCY

Click on image for link to original

LABORATORY FINDINGS

  • Impaired lactose tolerance test - minimal rise in blood glucose after ingestion of lactose;  diarrhoea occurs
  • Normal tolerance test of glucose and galactose - normal rise in blood glucose when the two monosaccharides are ingested separately;  no diarrhoea occurs
  • Decreased stool pH due to increased lactic acid
  • Increased stool lactose indicated by positive Clinitest reaction of stool


DISORDERS OF LIPID METABOLISM

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HYPERCHOLESTEROLEMIA

Familial hypercholesterolemia

Causes and Risks:
Affected people have consistently high levels of low-density lipoprotein, which leads to premature atherosclerosis of the coronary arteries. Typically in affected men, acute myocardial infarctions ( heart attacks ) occur in their 40s to 50s, and 85% of men with this disorder have experienced a heart attack by age 60. The incidence of heart attacks in women with this disorder is also increased, but delayed 10 years later than in men.

Individuals from families with a strong history of early heart attacks should be evaluated with a lipid screen. Proper diet, exercise , and the use of newer drugs can bring lipids down to safer levels.

It is possible for a person to inherit two genes for this disorder. This magnifies the severity of the condition. Cholesterol values may exceed 600 mg/cc. Affected individuals develop waxy plaques (xanthomas) beneath the skin over their elbows, knees, buttocks. These are deposits of cholesterol in the skin. In addition they develop deposits in tendons and around the cornea of the eye. Atherosclerosis begins before puberty and heart attacks and death may occur before age 30. Little of therapeutic value is presently available for this condition.

The incidence of familial hypercholesterolemia is 7 out of 1000 people.

Prevention:
In families with a history of familial hypercholesterolemia, genetic counseling may be of benefit, especially if both parents are affected. Prevention of early heart attacks requires recognition of existing elevated LDL levels, and a low-cholesterol, low-saturated fat , high-unsaturated fat diet in high-risk people may help to control LDL levels.

Symptoms:
  • a strong family history of early myocardial infarction
  • elevated and therapy-resistant levels of LDL in either or both parents
  • xanthomas (lesions caused by cholesterol deposits)
  • cholesterol deposits in the eyelids (xanthelasmas)
  • chest pain angina ) associated with coronary artery disease
  • evidence of obesity



Signs and Tests:
A physical examination may reveal xanthomas and xanthelasmas.

Laboratory testing may show:

  • elevated triglycerides
  • protein electrophoresis
  • total plasma cholesterol that is greater than 300 mg/cc (adult)
  • total plasma cholesterol that is greater than 250 mg/cc (children)
  • serum LDL that is higher than 200

Xanthoma



Treatment:
The goal of treatment is to reduce the risk of atherosclerotic heart disease and resulting myocardial infarction ( heart attack ).

Diet modification is the initial phase of treatment and is tried for several months before drug therapy is added. Diet modifications include reducing total fat intake to 30% of the total calories consumed. Saturated fat intake is reduced by decreasing the amounts of beef, pork, and lamb; substituting low-fat dairy products; and eliminating coconut and palm oil. Cholesterol intake is reduced by eliminating egg yolks and organ meats. Further reductions in the percentage of fat in the diet may be recommended after the initial trial period. Dietary counseling is often recommended to assist people with these adjustments to their eating habits.

Exercise, especially to induce weight loss , may also aid in lowering cholesterol levels .

Drug therapy may be initiated if diet, exercise, and weight reduction efforts have not reduced the cholesterol levels after an adequate trial period. Various cholesterol-reducing agents are available including:



Prognosis:
The outcome is likely to be poor in people with the homozygote type of familial hypercholesterolemia because it tends to be resistant to treatment.

The outcome of other types of familial hypercholesterolemia depends in part on the patient's compliance with treatment, but reduction in serum cholesterol levels can be achieved and may be significant in delaying a heart attack.

LABORATORY FINDINGS*


*These findings indicate Type IIa hyperlipoproteinemia.

ENDOGENOUS HYPERTRIGLYCERIDEMIA

Type IV Hyperlipoproteinemia
(Endogenous Hypertriglyceridemia; Hyperprebetalipoproteinemia)

A common disorder, often with a familial distribution, characterized by variable elevations of plasma triglyceride contained predominantly in very low density lipoproteins and a possible predisposition to atherosclerosis.

Depending on the level of endogenous triglyceride used to define type IV hyperlipoproteinemia, the disorder is common in American middle-aged men.

Symptoms, Signs, and Diagnosis

This lipidemia is frequently associated with mildly abnormal glucose tolerance (insulin resistance) and obesity and may be exaggerated when dietary fat is restricted and carbohydrate is added reciprocally (with caloric intake kept constant). Plasma is turbid, and triglyceride levels are disproportionately elevated. TC may be normal or slightly increased (frequently secondary to stress, alcoholism, and dietary indiscretion) and may be associated with hyperuricemia. Low HDL levels result from triglyceride elevation and often normalize when triglyceride levels are reduced.

Prognosis and Treatment

The prognosis is uncertain. The disorder may be associated with premature CAD.

Weight reduction and limitation of alcohol consumption, when applicable, are the most effective treatments and will often reduce the triglycerides to normal levels. Maintenance of proper body weight and dietary restriction of carbohydrate and alcohol are important. Niacin 3 g/day po or gemfibrozil 0.6 to 1.2 g/day po in divided doses will further reduce the lipidemia in patients whose levels are not controlled by diet. Large doses of somatic fish oils (8 to 20 g/day) are frequently very effective in treating hypertriglyceridemia due to elevated VLDL levels.

LABORATORY FINDINGS

Mild Form*

Severe Form**
HYPERCHYLOMICRONEMIA

*These findings indicate Type IV hyperlipoproteinenua,
**These findings indicate Type V hyperlipoproteinemia.

LABORATORY FINDINGS


DYSBETALIPOPROTEINEMIA

LABORATORY FINDINGS**


MIXED HYPERLIPIDEMIA

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LABORATORY FINDINGS




GOUT

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Click on image for link to original page

LABORATORY FINDINGS

  • Synovial fluid - white blood cells (WBC) 5,000/ul - 50,000/ul (avg 13,500); neutrophils 48% - 94% (avg 83%); increased complement.  Monosodium urate crystals are found free and also within WBC;  they are visualized when viewed microscopically under polarized light.  This finding establishes the diagnosis.  Urate crystals are also seen in biopsies of tophi.
  • Increased serum uric acid (more than 95% of patients)
  • Moderate leukocytosis during acute attacks
  • Increased urine uric-acid crystals and amorphous urates (10%-25% of patients)
  • Proteinuria - this precedes other evidence of renal disease
  • Decreased urine pH throughout the day due to inmpaired ammonia formation

PSEUDOGOUT

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Pseudogout results from a build up of calcium crystals (calcium pyrophosphate dihydrate) in a joint.  The joint reacts to the calcium crystals by becoming inflamed. The calcium deposits and chronic inflammation can cause parts of the joint structure to weaken and break down. Cartilage, the tough elastic material that cushions the ends of the bones, can begin to crack and get holes in it. Bits of cartilage may break off into the joint space and irritate soft tissues, such as muscles, and cause problems with movement.

Much of the pain of pseudogout is a result of muscles and the other tissues that help joints move (such as tendons and ligaments) being forced to work in ways for which they were not designed, as a result of damage to the cartilage. Cartilage itself does not have nerve cells, and therefore cannot sense pain, but the muscles, tendons, ligaments and bones do. After many years of cartilage erosion, bones may actually rub together. This grinding of bone against bone adds further to the pain. Bones can also thicken and form growths, called spurs or osteophytes, which rub together. 

The word 'pseudogout' actually means 'fake' or 'imitation gout.' Like the disease gout, pseudogout can come on as sudden, recurrent attacks of pain and swelling in a single joint. Gout is also caused by the build-up of crystals within a joint.  However, gout is caused by the build-up of uric acid crystals, rather than the calcium crystals.  Gout usually attacks the big toe, while pseudogout most often attacks the knee.

LABORATORY FINDINGS



HAEMOCHROMATOSIS

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Click on Image for link to original page

LABORATORY FINDINGS

  • Increased serum iron and transferrin saturation, marked
  • Decreased total iron binding capacity
  • Increased serum ferritin, marked - reflects increased body iron stores;  this gradually increases as the disease progresses
  • Increased serum glucose and decreased glucose tolerance - indicates development of diabetes as a result of pancreatic scarring from iron accumultion
  • Liver biopsy shows marked iron deposits in liver cells and in Kupffer's RE cells.


WILSON'S DISEASE
Wilson's disease causes the body to retain copper. The liver of a person who has Wilson's disease does not release copper into bile as it should. Bile is a liquid produced by the liver that helps with digestion. As the intestines absorb copper from food, the copper builds up in the liver and injures liver tissue. Eventually, the damage causes the liver to release the copper directly into the bloodstream, which carries the copper throughout the body. The copper buildup leads to damage in the kidneys, brain, and eyes. If not treated, Wilson's disease can cause severe brain damage, liver failure, and death.

Wilson's disease is hereditary. Symptoms usually appear between the ages of 6 and 20 years, but can begin as late as age 40. The most characteristic sign is the Kayser-Fleischer ring--a rusty brown ring around the cornea of the eye that can be seen only through an eye exam. Other signs depend on whether the damage occurs in the liver, blood, central nervous system, urinary system, or musculoskeletal system. Many signs would be detected only by a doctor, like swelling of the liver and spleen; fluid buildup in the lining of the abdomen; anemia; low platelet and white blood cell count in the blood; high levels of amino acids, protein, uric acid, and carbohydrates in urine; and softening of the bones. Some symptoms are more obvious, like jaundice, which appears as yellowing of the eyes and skin; vomiting blood; speech and language problems; tremors in the arms and hands; and rigid muscles.

Wilson's disease is diagnosed through tests that measure the amount of copper in the blood, urine, and liver. An eye exam would detect the Kayser-Fleischer ring.

The disease is treated with lifelong use of D-penicillamine or trientine hydrochloride, drugs that help remove copper from tissue. Patients will also need to take vitamin B6 and follow a low-copper diet, which means avoiding mushrooms, nuts, chocolate, dried fruit, liver, and shellfish. Taking extra zinc may be helpful in blocking the intestines' absorption of copper.

Wilson's disease requires lifelong treatment. If the disorder is detected early and treated correctly, a person with Wilson's disease can enjoy completely normal health.

LABORATORY FINDINGS



OSTEOMALACIA

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Classification of the Main Osteomalacias
 
MAIN ETOLOGIC DEFECT CAUSES MAIN CLINICAL FORMS
Vitamin D deficiency Dietary deficiency (Asian
(Elderly
(Small-bowel disease
25-hydroxyvitamin D2 deficiency 25-hydroxylase abnormality (Liver disease
Drugs
1.25 - dihydroxyvitamin D3 deficiency 1-alpha-hydroxylase failure Renal failure
1-alpha-hydroxylase deficiency Pseudo-vitamin D deficiency
Hypophosphataemia Decreased tubular phosphate reabsorption (Familial
(Sporadic
(Tumoral
Phosphate depletion Use of oral phosphate binds
(Nordin BEC, Peacock M. Aaron J et al:  Osteoporosis and osteomalacia.  Clin. Endocrinal Metab 9:177-205, 1980)

Usual Biochemical Abnormalities in Various Types of Osteomalacia
 
 
FASTING PLASMA VITAMIN-D-DEFICIENT RENAL FAILURE HYPOPHOSPHATAEMIA
Decreased calcium X X
Decreased phosphorus X X
Decreased calcium x phosphorous X X
Increased alkaline phosphatase X X
Increased parathyroid hormone X X
Decreased 25-hydroxyvitamin D3 X X
(Modified from Nordin BEC, Peacock M. Aaron J et al:  Osteoporosis and osteomalacia.  Clin. Endocrinol Metab 9:177-205, 1980)

LABORATORY FINDINGS

Laboratory Findings of Underlying Disorders



CYSTIC FIBROSIS
 

LABORATORY FINDINGS



DISORDERS OF PORPHYRIN METABOLISM

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ERYTHROPOIETIC PORPHYRIAS

Congenital Erythropoietic Porphyria

LABORATORY FINDINGS

Erythropoietic Protoporphyria

LABORATORY FINDINGS

HEPATIC PORPHYRIAS

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Acute Intermittent Porphyria

LABORATORY FINDINGS

Variegate Porphyria

LABORATORY FINDINGS

Heriditary Coproporphyria

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LABORATORY FINDINGS

Porphyria Cutanea Tarda

LABORATORY FINDINGS



AMYLOIDOSIS

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LABORATORY FINDINGS



DISORDERS OF BILIRUBIN EXCRETION

UNCONJUGATED HYPERBILIRUBINEMIAS

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Gilbert's Syndrome

LABORATORY FINDINGS

Crigler-Najjar Syndrome

LABORATORY FINDINGS

CONJUGATED HYPERBILIRUBINEMIAS

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Dubin-Johnson Syndrome

LABORATORY FINDINGS

Rotor's Syndrome

LABORATORY FINDINGS

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