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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3063_Библиотеки_им_академика_М_И_Перельмана
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Initial Management
Setting: inpatient hospital
Diagnostic/Therapeutic Plan
Test Results
CCS NOTE
In the case simulations, any patient admitted to the hospital can have a CBC,
chemistries, chest x-ray, and urinalysis. If the patient is age > 40, electrocardiogram is
Liver disease5.
Fibrinogen level
AST (SGOT)
ALT (SGPT)
Lactate dehydrogenase
Alkaline phosphatase
Bilirubin
Fibrinogen 500 mg/dL (normal 200–400 mg/dL)
AST 25 U/L (normal 10–30 U/L)
ALT 22 U/L (normal 10–40 U/L)
Lactate dehydrogenase 100 U/L (normal)
Alkaline phosphatase 88 U/L (normal)
Bilirubin 1.0 mg/dL (normal 0.2–1.0 mg/dL)
321
acceptable as a routine screening admission test. You do not lose points if the tests
show normal results.
Assessment
Abnormalities of the coagulation profile are due to factor(s) deficiency or, rarely, an inhibitor.
The intrinsic cascade is reflected in the PTT, whereas prolongation of the PT suggests a lesion
affecting the extrinsic cascade. Deficiencies arise because of congenital abnormalities
(hemophilia), consumption (DIC), or more commonly by inability to synthesize factors (liver
disease or vitamin K deficiency). Factor inhibitors are seen in patients with autoimmune
disease or in hemophiliacs who receive repeated infusions of concentrated products. This
patient has an elevated PT and PTT, with some evidence of bleeding.
DIC is unlikely because the patient is clinically improving, with no signs of sepsis, and the
platelet and fibrinogen levels are still normal. LFTs are normal; thus, liver failure is unlikely.
In hospitalized patients on antibiotics, the most likely etiology is a vitamin K deficiency. If the
patient does not respond to a trial of vitamin K, a mixing study can be performed. In the
presence of an inhibitor, the addition of normal plasma to the patient will not correct the
abnormality. All factor deficiencies must correct the PT and PTT to normal when mixed with
normal plasma.
Further Management Plan
CCS NOTE
Trial of subcutaneous vitamin K
Repeat PT and aPTT
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When PT and PTT are elevated, replacing vitamin K and checking for improvement is
a faster method of obtaining a diagnosis than obtaining specific factor levels.
Discussion
Vitamin K is a fat-soluble vitamin that is essential for the production of factors II, VII, IX, X,
and proteins C and S. It is essential for the gamma-carboxylation of these factors and is
necessary for their membrane-based activity. Warfarin inhibits this process and produces a
coagulation defect identical to vitamin K deficiency. Vitamin K is absorbed by the small
intestine and stored in the liver. It is also produced endogenously in the GI tract by the native
bacterial flora. Deficiency occurs in 3 settings: poor intake, malabsorption, and loss of storage
sites due to liver disease.
Acutely ill patients often become deficient due to poor oral intake and sterilization of the gut
due to broad-spectrum antibiotics. It is also commonly seen in severe liver disease. Initially
only the PT is elevated because factor VII has the shortest half-life in the cascade.
The INR is used to monitor therapy with warfarin. The INR is not necessary when initially
assessing clotting factor levels and function. Vitamin K supplementation can be done
parenterally but anaphylaxis can be seen. Fresh frozen plasma can be given when severe
bleeding occurs.
Follow-up management and prevention
Final Diagnosis
Coagulation defect due to vitamin K deficiency
Continue vitamin K for 3 days
Pneumococcal vaccine
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Case 5
Chief Complaint
Fatigue, recurrent upper respiratory infections, and frequent bruising
History and Physical Examination
A 25-year-old woman comes to the clinic because of progressive fatigue over the last 6
months. She has also noticed frequent colds and several sinus infections, which she never
experienced in the past. Over the last 2 months she notes multiple bruises on her arms and
legs without a history of obvious trauma. Her periods have also been particularly heavy,
lasting 7 days. She denies recurrent fever and weight loss. Her appetite is intact, and she
has no abdominal pain or fullness. The patient currently is unemployed but had worked as
a painter for several years. She takes no medications.
Upon physical examination her temperature is 38 C (100.4 F), blood pressure 100/70 mm
Hg, and pulse 100/min. She appears pale. With the exception of multiple bruises seen on
her extremities, the remainder of the physical examination is normal.
CCS NOTE
Most of the case simulations will not give you laboratory test results in the history. You
need to order the tests.
325
Differential Diagnosis
Initial Management
Setting: emergency department
Diagnostic/Therapeutic Plan
Test Results
Aplastic anemia
1.
Acute leukemia
2.
Vitamin B12 or folate deficiency
3.
Paroxysmal nocturnal hemoglobinuria
4.
Drug- or toxin-induced marrow failure
5.
Myelofibrosis
6.
HIV
7.
Systemic lupus erythematosus
8.
Peripheral smear
Absolute neutrophil count
HIV test
Chest x-ray, urinalysis, blood cultures
ANA
B12 and folate
Peripheral smear: no immature forms seen, no increase in reticulocytes, mean corpuscular
volume 100 fL (normal 800–100 fL)
Absolute neutrophil count: 500/mm
3
(low)
HIV: negative
Chest x-ray, urinalysis, blood cultures normal
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CCS NOTE
All patients with anemia should have a peripheral smear. A smear is most useful in
macrocytic anemia and hemolysis.
Assessment
The differential diagnosis for pancytopenia is extensive and includes premature destruction of
cells due to hypersplenism or autoimmune disease, marrow suppression secondary to
nutritional deficiency (vitamin B12, folate), infection (tuberculosis, HIV), drugs (trimethoprim-
sulfamethoxazole, chloramphenicol), or malignant infiltration. Drug-induced pancytopenia is
usually dose-dependent and reversible. A rare idiosyncratic reaction to chloramphenicol is
associated with irreversible marrow failure. Nucleated RBC on the peripheral smear are
suggestive of marrow fibrosis or infiltration. There are no abnormal white blood cell forms on
peripheral smear. The most likely cause is aplastic anemia, which may be related to her
exposure to paints.
Paroxysmal nocturnal hemoglobinuria may also present with a hypocellular marrow, although it
is more commonly associated with hyperplasia of red blood cell precursor populations.
Myelodysplasia may also yield a hypocellular biopsy but is usually associated with a
hypercellular specimen with abnormal features of maturation and characteristic findings
(deletion of chromosomes 5 or 7). Other potential etiologies for a dry aspirate include hairy
cell leukemia, myelofibrosis, and M7 (megakaryocyte) acute myeloblastic leukemia (AML).
Hairy cell leukemia is associated with characteristic abnormalities on immunophenotyping.
ANA negative
B12 and folate normal
327
Tartrate-resistant acid phosphatase (TRAP) staining is no longer considered accurate enough
and diagnosis should be made based on morphology.
Further Management Plan/Results
CCS NOTE
A consultant will arrive within 15 minutes if a consult is ordered “stat.” A consultant
will never tell you which specific tests or treatments to order.
Discussion
Aplastic anemia is characterized by pancytopenia, thought to be due to stem cell injury. This
can be acquired or congenital. In the acquired form, a known insult (such as one of the above
toxins), drug, or infection is found in about 50% of cases.
Several drugs are associated with aplasia, such as indomethacin, gold, phenylbutazone,
sulfonamides, phenytoin, nifedipine, and quinacrine. Chloramphenicol is associated with a
dose-related pancytopenia and with an idiosyncratic, rare, profound, pancytopenia not related
to dose.
Other causes of marrow aplasia include:
Bone marrow
biopsy
Unable to aspirate; biopsy profoundly hypocellular with fat replacing most
hematopoietic elements
No increase in reticulin fibers seen
Bone marrow for AFB stain and fungal forms negative
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A careful history of prior toxin exposure is crucial because removal of the offending agent may
reverse the disease.
In some cases, aplastic anemia is thought to arise from immune-mediated injury of stem cells.
This is supported by the finding that some patients have been shown to respond to
immunosuppressants such as antithymocyte globulin (ATG) and cyclosporine. Bone marrow
transplant is often only successful when preceded by high-dose chemotherapy to eradicate the
existing host immunity prior to transplant. Bone marrow transplant is also curative and is the
best therapy in patients age <70 in good health and with an HLA-matched donor.
The clinical presentation includes bleeding, anemia, and recurrent infections. The latter is of
particular concern in patients with neutrophil count <500/mm
3
, who are at risk for nadir sepsis.
The first principle in treatment is removal of the offending toxin or agent. Those patients who
are fit and have HLA-matched siblings should undergo bone marrow transplantation. If
possible, patients should not be transfused prior to transplant to avoid sensitization and
rejection of the future graft. Those patients who are elderly or have no donor are given trials of
immunosuppressive agents.
Follow-up Management
Toxins such as benzene, arsenic, toluene found in glue, insecticides, paint thinners, and
lacquers
Infections such as hepatitis C and infectious mononucleosis
Radiation and chemotherapeutic agents
Occasionally, HIV and parvovirus (usually cause red cell aplasia but occasionally can
cause aplastic anemia)
Removal of offending toxin if one is present
Hematology consult to consider bone marrow transplantation in those age <50 with a
matched donor
Trial of immunosuppressive therapy with anti-thymocyte globulin and cyclosporine if
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Final Diagnosis
Pancytopenia, aplastic anemia
transplant is not an option
Alternate immunosuppressive medications are mycophenolate or cyclophosphamide
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