Pathophysiology lab questions

Laboratory evaluation of hemostatic disorders

1. A 46-year-old obese woman was admitted to the hospital with subfebrility and malaise. Her right thigh is swollen, with tight skin and dilated superficial veins. A day ago she started complaining of nausea, sweating, dyspnea and chest pain. Laboratory data:
RBC: 4.1 T/l; WBC: 13 G/l; PLT: 240 G/l
ESR: 25 mm/h
LDH: 600 U/l
CK: 160 U/l
D-dimer: high (> 3 μg/ml)
AT-III concentration: 60 % of normal

What may cause her symptoms? What tests would you perform to support your diagnosis?

Clinical findings:
Swollen right thigh with tight skin and dilated superficial veins - suspect DVT.
DVT accompanied by chest pain and dyspnea are signs of pulmonary embolism or AMI (should always include AMI - suspect the worst).

Lab findings:
- RBC (3,8-5,2 T/l) - 4,1 T/L is normal.
- WBC (4-10 G/l) - 13 G/l is a bit above normal, most likely due to an inflammation (also, the thormbus serves as an ideal site for bacterial growth).
- PLT (150-400 G/l) - 240 G/l is within the normal range.
- ESR (< 20 mm/h) - 25 mm/h is slight increased, and could result from an ongoing inflammation.
- LDH (< 160 U/l) - 600 U/l is quite high. LDH in this case may either be released during lysis of RBC (DVT/PE), or from ischemic cardiomyocytes (if there is an AMI).
- CK (< 200 U/l) - 160 U/l is within the normal range. If the patient have AMI we would see an elevation in this value.
- D-dimer (> 3 μg/ml) - High. This is a type of fibrin degradation product (from cross-linked fibrin). Elevation may be caused by DVT and PE (must not rule out DIC based on this isolated finding).
-AT-III concentration - 60% of normal. Decreased AT-III concentration will cause hypercoagulability (Virchow’s triade). May be inherited.

Conclusion:
The patient has a DVT and most likely a PE due to the DVT. Most likely NOT a PE that resides in the pulmonary trunk (saddle embolus) or segmental arteries, because this usually cause sudden death.

Further tests that can be made:

- Chest X-ray - Usually performed before CTPE.
- CT pulmonary angiogram (golden standard) - Non invasive method that uses CT technology to obtain an image of the pulmonary arteries. Iodine contrast agent is preferred. It is made after chest X-ray, when there is positive D-dimer and there is clinical signs for PE.
- ECG - It is usually made when there is chest pain. During acute PE, the ECG will show a S1Q3T3 syndrome (large S in lead I, deep Q in lead III, along with an inverted T also in lead III). This is due to the sudden right-sided strain (it strengthens the diagnosis).

2. A 45-year-old woman visits her physician for poor health and recurrent fever. She has been troubled by menorrhagia, bleeding after slight traumas and frequent nosebleeds in the last few months.

Her laboratory parameters: platelet count: 8 G/l bleeding time: 15 min prothrombin time: INR = 1.00 aPTT: 40 sec fibrinogen concentration: 3 g/l (normal).

What is the possible cause of her bleeding disorder?

Clinical findings:
Patient has menorrhagia (heavy/prolonged and irregular menstruation), frequent epitaxis and bleedings after minor traumas.

Lab findings:
- PLT (150-400 G/l) - 8 G/l is critically low (thrombocytopenia).
- Bleeding time (3-8 min) - 15 min is prolonged. The test is measuring the ability of the platelet to stop a minor bleeding (corresponds to the low platelet count).
- INR (0,8-1,2) - 1,0, is normal. Indicating that the extrinsic and common pathway function properly.
- aPTT (35-45 sec) - 40 sec is also normal, indicating that the intrinsic pathway also function properly.
- Fibrinogen concentration (3 g/l) - Normal.

Conclusion:
Since the aPTT and INR is normal, we can exclude any disorders related to the coagulation system. However, the platelet count is severely reduced, and the bleeding time is increased, indicating thrombocytopenia.
The reason for the thrombocytopenia may be:
- Acute leukemia (the tumor cells interferes with normal synthesis in the bone marrow, causing a drop in all cells that derive from the bone marrow).
Idiopathic thrombocytopenic purpura is also a possibility. It is defined as isolated low platelet count with normal bone marrow. It is an autoimmune condition with characteristic purpurish rash and increased bleeding tendency.

3. The patient is a 28-year-old female who has pronounced bleeding after tooth extraction and menorrhagia, which has caused repeatedly an iron deficiency anemia. Bleeding from cuts is prolonged and large hematomas may appear after bruising. A brother of the patient and her son are affected by a similar bleeding tendency. Laboratory data: platelet count: 176 G/l bleeding time: longer than 30 min platelet adhesion: abnormal
ADP induced aggregation: normal clot retraction: normal aPTT: 55 sec thrombin time: 21 sec.

What is the most likely diagnosis?

Clinical findings:
A genetic disorder that cause increased bleeding tendency, which is most likely not X-linked (female patients are usually carriers). The iron deficiency can be explained by the pronounced bleeding.

Lab findings:
- PLT (150-400 G/l) - 176 G/l is towards the lower limit, but still in the normal range.
- Bleeding time (3-8 min) - > 30 min is severely prolonged. This result indicates a problem with platelet function (normal PLT count).
- Platelet adhesion - Abnormal, indicating that it could be a problem with the platelets or the surfaces the platelets adhere to (collagen or vWF).
- ADP induced aggregation test - Normal. This indicates that there is not a problem with the platelet function, but rather the surfaces the platelets adhere to.
- aPTT (35-45 sec) - 55 sec. It is increased, which usually indicates either a problem with the intrinsic or the common pathway. In this case the increased aPTT is caused by the lack of vWF (vWF usually binds to factor VIII and keeps it in close proximity to the coagulum, without vWF there will be decreased XIII).
- Thrombin time (20-22 sec) - 21 sec. Indicate no problem with the common pathway (thrombin/fibrinogen/etc).

Conclusion:
The disease we suspect is Von Willebrands disease. This is an inherited disease where the patient does not have vWF, thus decreased attachement for the platelets (increased bleeding tendency).

4. A 41-year-old woman has had 3 spontaneous abortions and later gave birth to a premature baby.
She was diagnosed to have SLE 5 years ago. She has been admitted to the hospital today with a strong pain in her left leg.
Some of her laboratory test results:
WBC: 10 G/l
ESR: 20 mm/h
D-dimer: strongly positive (> 3 μg/ml) aPTT: 62 sec thrombin time: 20 sec

What can be the cause of her complaints, and how can we prove it?

Clinical findings:
Patient diagnosed with SLE, had 3 spontaneous abortions, admitted due to strong pain in her left leg (DVT?).

Lab findings:
- WBC (4-10 G/l) - 10 G/l is in the upper limit of the normal range.
- ESR (< 20 mm/h) - 20 mm/h is also in the upper limit of the normal range.
- D-dimer (> 3 μg/ml) - Strongly positive. Indicates DVT, PE (or DIC). Can be associated with the strong pain in the left leg.
- aPTT (35-45 sec) - 62 sec. With increased aPTT we would normally suspect coagulopathy involving the intrinsic pathway, but in the case of SLE the body produces lupus anticoagulant (lupus antibody). This antibody bind to phospholipids and in vivo increase the clotting tendency (name is a misnomer regarding its function in vivo - Is an anticoagulant in vitro). NB - aPTT is done IN VITRO, thus increase clotting time.
- Thrombin time (20-22 sec) - 20 sec is normal. Telling us that the common pathway function properly.

Conclution:
Patients with SLE tend to develop antiphospholipid syndrome (Hughes syndrome). In this disease, antiphospholipid antibodies (lupus anticoagulant, anti-cardiolipin, anti-B2-glycoprotein) leads to a hypercoagulable state, and thrombus may occur in both arteries and veins - In this case a DVT in the left leg. This disease is also the reason for the spontaneous abortions and preterm delivery (common in this disease).

How can we prove it:

- Direct antiphospholipid assay (ELISA). Serological tests targeting the different AP antibodies, in this case lupus anticoagulant.
- Must also prove that the prolonged aPTT is not due to hemophilias (coagulation factor deficiencies).

Other principal tests are:
- aPTT (done).
- Dilute Russel’s viper venom time.
- Kaolin clotting time.
- Prothrombin time (with lupus sensitive thromboplastin/TF).

5. A 3-year-old boy, who suffered from frequent hematomas since he first started to walk, developed a large swelling on his head following a fall. After admission to hospital the surgeon was looking for an abscess, but found blood instead. He is slightly anemic.
Laboratory parameters: platelet count: 164 G/l bleeding time: 4 min prothrombin time: INR = 1.12 aPTT: 60 sec thrombin time: 20 sec euglobulin lysis time: 140 min, normal

What tests are necessary to establish a diagnosis?

Clinical findings:
Slightly anemic boy with increased bleeding tendency.

Lab findings:
- PLT (150-400 G/l) - 164 G/l, is within the normal range.
- Bleeding time (3-8 min) - 4 min, within the normal range. Both the BT and the platelet count indicate that there is no thrombocytic problem.
- INR (0,8-1,2) - 1,12, is within the normal range, indicating no problem with the extrinsic and common pathway.
- aPTT (35-45 sec) - 60 sec, indicate a problem in the intrinsic pathway.
- Thrombin time (20-22 sec) - 20 sec, is within the normal range and indicate no problem with the common pathway.
- Euglobulin lysis time - 140 min is normal. The test measures overall fibrinolysis, thus in this case there is normal fibrinolysis.

Conclusion:
The aPTT indicated that there is a problem with the intrinsic coagulation pathway, thus a coagulation factor deficiency most likely.
Hemophilia is an X-linked, coagulation factor deficiency disorder:
VIII deficiency - Hemophilia A (80%).
IX deficiency - Hemophilia B (20%).
XI deficiency - Hemophilia C, extremely rare and occur only in ashkenazi jews (jewish ethnic division originating from the middle east).

Tests to establish diagnosis:

- Measure the serum levels of the specific coagulation factors diectly.

- Before the fancy equipment, hemophilias were diagnosed by mixing the serum sample of the boy with a prepared sample that does not contain the coagulation factor we suspect are deficient - usually factor VIII (No clotting - no factor VIII in the boys serum/Clotting - The boy’s serum contain factor VIII, thus he must be deficient of factor IX).

6. The patient is a 27-year-old pregnant woman without a history of bleeding symptoms. She is in her
38th week of pregnancy with her fourth child. Four hours before admission she suddenly experienced a severe pain in the abdomen followed by start of birth pains that were almost continuous. Half an hour after admission she lost some blood from her vagina that did not clot. The uterus was found totally contracted on physical examination. Fetal hearts sounds are not detectable.

Laboratory data: platelet count: 20 G/l bleeding time: 8 min prothrombin time: INR = 4.29 aPTT: 80 sec thrombin time: 30 sec.

What is the probable cause of bleeding? How do you think the FDP concentration changes in this condition?

Clinical findings:
Patient is pregnant and felt sudden pain in the abdomen. Four hours later she has bloody discharge from her vagina that do not clot. There are no fetal heart sounds.

Lab findings:
- PLT (150-400 G/l) - 20 G/l is severely low. Indicated thrombocytopenia.
- Bleeding time (3-8 min) - 8 min is in the upper limit of the normal range.
- INR (0,8-1,2) - 4,29. This indicates that there are problems in the extrinsic or common pathway.
- aPTT (35-45 sec) - 80 sec is also severely prolonged, indicating problems with the intrinsic or common pathway.
- Thrombin time (20-22 sec) - 30 sec indicate problems with the common pathway.

Conclusion:
This woman has a severly reduced ability to stop bleedings. The most probable cause is disseminated intravascular coagulopathy (consumed platelets, coagulation factors, etc). DIC may be caused by obstetric conditions such as abruptio placentae (cause large loss of blood), pre-ecclampsia (not proper development of the spiral arteries during placental developmen, leading to ischemia in the placenta and release of substances that cause systemic endothelial damage in the mother), or amniotic fluid embolism.

The fibrin degradation product concentration (especially D-dimer) will be increased in the case of DIC.

7. A 34-year-old previously healthy woman suddenly got sick after having arrived to her hotel from a long air trip. She has dyspnea and hemoptysis. She is found to have tachypnea, tachycardia and distended neck veins on physical examination.
What is the most likely diagnosis, and what tests can we use to support it? What may be the cause of the problem?

Clinical findings:
Long air trips cause stasis of blood, and increased risk for thrombus formation (tourist class syndrome). The fact that the patient has dyspnea, hemoptysis, tachypnea, and distended neck veins indicate that there is a right sided stasis most likely due to venous thrombus formation with pulmonary embolism.

The cause of the problem:
All congenital and acquired diseases that may cause thrombus formation. Ex:
- Leiden (factor V) mutation - Factor V cannot be inactivated by protein C, thus create a hypercoagulable state.
- Congenital lack of antithrombin III (no effect of heparin) and protein C/S.
- Birth control pills and smoking.
- Prothrombin gene mutation.
Dysfibrinogenemia.

Tests:

- ECG - Rule out AMI (may find S1Q3T3 syndrome).
- Chest X-ray - Always performed if we suspect pulmonary embolism.
- CT pulmonary angiography - Visualize pulmonary arteries.
- Screen for the different hypercoagulable disorders.

8. A 53-year-old woman has a bleeding tendency since she was a child. She got a bump on her forehead two day ago, and now has a dark, purple periorbital hematoma. Laboratory findings: platelet count: 250 G/l bleeding time: longer than 30 min prothrombin time: INR = 1.16; aPTT: 30 sec; thrombin time: 20 sec platelet adhesion and aggregation: decreased clot retraction: less than normal.
What may cause her bleeding tendency?

Clinical findings:
Had increased bleeding tendency since she was a child, and now she has a periorbital hematoma due to a bump in the head.

Lab findings:
- PLT (150-400 G/l) - 250 G/l is within the normal range (no thrombocytopenia).
- Bleeding time (3-8 min) - > 30 min, indicates that there is a problem with the platelets (thrombocytopathy because the platelet count is normal), or the surface to which the platelets adhere to.
- INR/aPTT/TT - Within normal range, indicating no problems with the coagulation pathways.
- Platelet adhesion and aggregation is decreased. Usually due to glycoprotein deficiencies in the platelet membrane.

Conclusion:
The bleeding tendency involves the platelets. Since the count is normal, the problem must lie with the function. In this case we then either suspect:
Glanzmann’s thrombasthenia (aut. rec.) - Platelets have defective or low levels of GP IIb/IIIa (bind fibrinogen).
Bernard-Soulier syndrome (aut. rec.) - Platelets have defective GP Ib (bind vWF).
Acquired thrombocytopathy - Drug induced (ex. aspirin).

9. A 76-year-old male has been on anticoagulant therapy for years because of his chronic atrial fibrillation. He has been recently treated with a broad-spectrum antibiotic for his febrile illness. He has been complaining of frequent nosebleeds since yesterday. His stools have turned tar-like.
What can be the cause of his complaints and what is to be done?

Clinical findings:
Chronic atrial fibrillation, febrile illness (bacterial infection), and now frequent nose bleedings (epitaxis) and tar-like stools (melena).

Conclusion:
Patients with atrial fibrillation is usually prescribed with anticoagulant treatment like warfarin (coumarine). This is a vitamin K epoxidase reductase inhibitor that antagonize vitamin K recycling in the liver, thus inhibit the production of certain coagulation factors. Vitamin K is normally produced by certain E. coli strains in the normal gut flora.

When the patient was treated with broad-spectrum antibiotics, the vitamin K-producing bacteria was killed together with the pathogenic ones. The lack of vitamin K and the continuous use of warfarin increase the bleeding tendency of the patient - Explains the frequent epitaxis.
The tar-like stool can be explained by the development of for example pseudomembranous colitis (Clostridium difficile is usually suppressed by normal flora bacteria, but when the good bacteria are gone, the bad ones dance on the table). The colitis cause small bleedings that does not stop due to the increased bleeding tendency —> Bloody stool.

What is to be done:
Inject vitamin K to restore the normal level, treat the pseudomembranous colitis with vancomycin and metronidazole, and give probiotics after to restore normal flora. Fix-finito!