Saturday, October 6, 2012

Biochemistry-Spotters

by Dr. Namrata Chhabra

Case study-1

A 56- year-old man who smoked heavily for many years developed worsening cough with purulent sputum and was  admitted to the hospital because of difficulty in breathing. He was drowsy and cyanosed. His X- ray chest and arterial blood gas analysis findings were as follows;











(X- Ray chest- PA view)
Arterial blood gas analysis-
pH -  7.2
p CO2 – 70 mm Hg
HCO3- - 26 mmol/L
PO2 - 50 mm Hg
What is the most likely diagnosis? Write two points in favor of your answer.
Answer- It is a case of Respiratory acidosis,  as evident from low p H and high p CO2. The most likely cause is Chronic obstructive Pulmonary disease (COPD).

Case study-2

 A 24 year female with broken ankle was brought to emergency with acute pain.











X-Ray showing ankle fracture
Blood gas analysis revealed the followings-
 pH- 7.55                  
PCO2- 27 mm Hg
PO2     - 105 mm Hg
HCO3-   23 mmol/L
What is the probable diagnosis?
Comment on the renal Glutaminase activity for this patient as a mechanism of compensation.
Answer- It is a case of Respiratory alkalosis, as evident from high pH, low p CO2 and near normal bicarbonate levels.It might be due to hyperventilation induced by acute pain.The renal glutaminase activity will decline so as to limit the excretion of H+ ions to restore pH back to normal.

Case study-3

An elderly couple was brought by ambulance to the emergency department after their daughter noticed that they were both acting “strangely.” The couple had been snowed in at their house until the snowplows cleared the roads. They had plenty of food and were kept warm by a furnace and blankets.












Their daughter noticed that they both were complaining of bad headache, confusion, fatigue, and some nausea.
On arrival to the emergency department, both patients were afebrile with normal vital signs .Their lips appeared to be very red. Both patients were slightly confused but otherwise oriented. The physical examinations were within normal limits.
Carboxyhemoglobin levels were drawn and were elevated.
What is the most likely cause of these patients’ symptoms?
Answer- It is a case of CO poisoning as evident from clinical manifestations and levels of elevated Carboxyhemoglobin. Carbon monoxide is a colorless, odorless gas produced by the combustion of carbon-containing materials. Mechanisms of CO toxicity are not completely understood. They appear to involve the followings-
1) Carbon monoxide avidly binds to hemoglobin, with an affinity approximately 250 times that of oxygen. This results in displacement of O2 from Hb resulting in reduced oxygen-carrying capacity and altered delivery of oxygen to cells.
2) Binding of CO to hemoglobin causes an increased binding of oxygen molecules at the 3 other oxygen-binding sites, resulting in a leftward shift in the oxyhemoglobin dissociation curve and decreasing the availability of oxygen to the already hypoxic tissues.
3) Inhibition of mitochondrial electron transport chain
4) Possibly direct toxic effects on brain tissue

Case study-4

A 54 –year- old woman who was bed bound in a nursing home began to develop swelling of her left leg.











She was evaluated with venous Doppler ultrasound and was found to have a deep vein thrombosis. She was immediately started on heparin to prevent the clot from further enlarging.
What is the chemical nature of Heparin?
How will it help in preventing the clot formation?
Answer Heparin also called α Heparin, is a highly sulfated GAG (Glycosaminoglycans). It is an anticoagulant widely used in clinical practice. It produces its major anticoagulant effect by inactivating thrombin and activated factor X (factor Xa) through an antithrombin (AT) dependent mechanism. Binding of Heparin to antithrombin produces conformational changes which promote the binding of the latter to serine protease “thrombin” which is inhibited, thus fibrinogen is not converted to fibrin and the coagulation is inhibited.

Case study-5

A 25 –year-old women presents, with a history that includes-
a) Hepatosplenomegaly with eventual removal of spleen
b) Bone and joint pains with several fractures of femur.
c) A liver biopsy that shows wrinkled looking cells with accumulation of Glucosyl ceramide,






















What is the likely diagnosis for this patient?
What is the possible defect in this disease?
Answer- It is Gaucher's disease, caused due to deficiency of Beta glucosidase enzyme. Hepatosplenomegaly, skeletal changes and wrinkled looking cells are diagnostic of this disease. All symptoms are due to toxic effects of undegraded cerebrosides.

Case study-6

 A 4 -year-old boy was brought for consultation for hematuria, edema of lower extremities as well as swollen right leg. The child was fed only with cow’s milk and biscuits.
From the period of five months, the boy manifested irritability, sweating, poor appetite and cried when somebody touched him
At admission the baby was afebrile, pale, and malnourished; his hair was dry and cracked. Clinical evaluation showed no organomegaly, no neurological signs, gingival bleeding was there.











Laboratory findings were as follows
Red Blood Cell Count 3.5 million/mm3
Hemoglobin (Hb) 7 g/dl
Haemtocrit (Hct) 30%
Serum Iron low
Massive sub periosteal hematoma on the right femur, dilatated metaphyses and general osteoporosis had been present on the radiogram.
What is the probable diagnosis for this child?
What is the defect in this disease?
Answer- It is a case of Scurvy caused due to vitamin C deficiency. Bleeding from multiple sites after a minor trauma and iron deficiency anemia are diagnostic of vitamin C deficiency.

Case study-7

A 15 –year-old girl presented with abdominal pain and diarrhea for 3 days. She became jaundiced and a presumptive diagnosis of infective hepatitis was made, but serological tests were negative. She subsequently died of fulminant liver failure. At post-mortem her liver copper concentration was found to be grossly increased. A brown ring at the edge of the iris was observed











What is the probable diagnosis?
What is the defect in this disease?
Answer- This is a case of Wilson's disease (Hepato lenticular degeneration ) caused due to excessive accumulation of copper. The Kayser Fleischer ring shown in the picture is diagnostic of this disease

Case study-8

A 24 –year –old male suffering from Malaria was put on Primaquine. He developed malaise, fatigue and yellow discoloration of sclera and skin.











On examination – There was
 Pallor- ++, Icterus ++, Pulse – 100/min., Temperature 102°F
Liver and spleen were palpable.
The investigation report was as follows-
Hb -5.gm%
TLC-13000 cmm esp. polymorphs
Serum bilirubin- 6 mg%
Van den Bergh- Indirect positive.
Urine- Hemoglobin + and Urobilinogen +
The color of the urine was brownish black
What is the probable diagnosis?
What is the relationship of Primaquine intake and the present manifestations?
Answer- This is a case of Glucose-6-Phosphate dehydrogenase deficiency. Primaquine (Antimalarial drug), a pro oxidant causes precipitation of this defect by inducing hemolysis due to failure to decompose H2O2. Vanden Bergh indirect positive, the presence of hemoglobin and urobilinogen in urine are indicative of hemolytic jaundice in this condition.

Case study-9

 An Rh negative mother delivers a baby who develops jaundice immediately after birth.












General Examination reveals-                            
Heart Rate    80/min
Icterus            +
Irritability     +
Liver            Palpable
Laboratory Investigations
Serum
Bilirubin
  • Total              10 mg%
  • Indirect        7 mg%
  • Direct            3 mg%
Alkaline phosphatase    50 U/L
Urine          
Urobilinogen           +++
Feces
Stercobilnogen        +++
What is your likely diagnosis?
What is meant by direct and indirect Bilirubin?
Answer- This is most probably a case of Rh incompatibility Baby has hemolytic jaundice as evident from the biochemical findings-indirect hyperbilirubunemia, positive urobilinogen and absence of bilirubin in urine with positive stercobilinogen in feces.
Conjugated bilirubin gives direct and immediate reaction with Van den Bergh reagent, hence it is called direct bilirubin, while unconjugated being water insoluble does not react with Vanden Bergh reagent, methanol is added in an amount sufficient to make it soluble and react with reagent to give the test positive . The reaction is positive only upon addition of methanol, hence called indirect bilirubin.

Case study-10

At the age of 11 months, a boy showed signs of delayed motor development and was brought for consultation. His mother had noticed sand like crystals on the diaper of the baby but reported only when asked particularly about it. History revealed that the child had a compulsive urge to bite his lips and fingers. Upon questioning the mother revealed that she had a brother with similar symptoms.

 










The Lesch Nyhan syndrome was suspected, urinary and serum uric acid levels were estimated. Both were abnormally high for the boy’s age. The diagnosis was confirmed by estimating enzyme levels in skin fibroblasts; the enzyme activity was 50 % of the normal.
Which enzyme is deficient in Lesch Nyhan Syndrome?
Answer-  There is deficiency of HGPRT (Hypoxanthine guanine phospho Ribosyl Transferase) enzyme. This is an enzyme of Salvage pathway of purine nucleotide biosynthesis.

Case study-11

A 65 –year-old man reported with visible Jaundice which he had noticed to be deepening in color. There was no history of pain, fever or any drug intake, but he complained of some weight loss and pale stools from the past few days. There was no history of such like episode before.











Blood Biochemistry revealed-
Serum Total bilirubin- 20mg/dl
AST-87 U/L
ALT- 92 U/L
ALP-350 U/L
What is the likely diagnosis?
Which type of Bilirubin is expected to be present in the circulation?
Answer- This is a case of obstructive jaundice. Cause might be carcinoma head of the pancreas , since history of weight loss is there. High level of Alkaline phosphatase is observed in obstructive jaundice. High level of transaminases might be due to associated liver cell injury as a result of cholestasis. Conjugated bilirubin will be there in circulation.

Technique

1)  Identify the technique shown in the picture
2) What are the indications for its usage?

















Answer- This is southern hybridization (Blotting), undertaken for analysis of DNA fragments.

Technique

1) Identify the technique shown in the picture
2) What are the indications for its usage?












Answer- This is paper electrophoresis, used for separation of proteins and amino acids.

Make a diagnosis

Glucose tolerance curve of two patients are shown in the picture-
1)  Pateint  (A)  with a dark line
2)  Patient  (B) with a faint line















Comment on the glycemic status of these two individuals.
Answer-1) A- Normal glucose tolerance curve
2) B- Diabetic curve (High fasting and pp values)

Crystals
Following are the Laboratory findings of a patient brought to the hospital in a state of coma-
Blood p H- 7.2
Serum bicarbonates- 16mmol/L
Urine test- Reducing sugars-++, Ketones- +, proteins- traces.
The osazone test is performed for the confirmation of the identity of the reducing sugar.













Identify  the crystals and comment on the findings giving a probable diagnosis for this patient.
Answer- These are glucosazone crystals.
The patient is suffering from diabetic keto acidosis.



------------------------------------------ Best Wishes: Dr.Ehab Aboueladab, Tel:01007834123 Email:ehab10f@gmail.com,ehababoueladab@yahoo.com ------------------------------------------
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