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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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Further Management Plan/Results
5 ng/mL (low)
Low
High
High
CLINICAL PEARL
Iron studies must always be ordered before a transfusion is given. However, you do not
have to wait for their results to give the transfusion.
Discussion
Iron deficiency is the most common nutritional deficiency in the world. It is believed that as
many as 30% of the world’s population may be anemic, and approximately 50% are believed
to be iron deficient. In the United States, 20% of women of childbearing age are iron-deficient.
Daily iron losses from the skin and GI tract are approximately 1 mg for men and 1.5 to 2 mg for
women. Daily iron intake is 10–20 mg a day in the United States but it is poorly absorbed.
Iron is primarily absorbed in the duodenum and proximal jejunum. Heme iron (meat) is better
absorbed than non-heme iron. The latter requires the presence of stomach acidity and may be
Ferritin
Iron
TIBC
RDW
341
compromised in achlorhydria. Iron absorption is decreased by antacids and increased by
ascorbic and citric acid. Iron absorption is also regulated by iron stores and increases during
pregnancy and hemorrhage. Iron binds to transferrin in the circulation, which serves as a
carrier molecule. It binds to apoferritin and is stored primarily in bone marrow and in the
reticuloendothelial system as ferritin. Hemosiderin is a degraded form of ferritin that
accumulates in iron overload.
Women are particularly at risk for iron deficiency due to increased losses secondary to
menstrual bleeding, particularly if there is no iron supplementation in the diet. Pregnancy adds
further risk in that the fetus takes approximately 750 mg of iron from the mother during
gestation such that without supplementation, women will uniformly deplete their iron stores and
become deficient by time of delivery. Infants are also susceptible, particularly if they are
breast-fed and have no exogenous source of iron. Adolescents are susceptible because of
increased iron requirements. Another cause, particularly in older patients, is occult GI
bleeding. Iron deficiency due to malabsorption is less common and is seen in processes that
diffusely affect the proximal small bowel, such as celiac and tropical sprue, giardiasis, or
bacterial overgrowth.
Iron deficiency develops gradually. First iron stores are depleted. Then erythropoiesis is
blunted, and anemia finally develops. Patients with longstanding anemia can occasionally
develop glossitis and stomatitis due to dysfunction of iron-dependent enzyme systems that
maintain epithelial cell integrity. Brittle fingernails and classic spooning of the nails can be
seen. Patients can develop esophageal webs, resulting in dysphagia. This is known as the
Plummer Vinson syndrome and may be a premalignant lesion. Pagophagia (craving for eating
ice) is quite specific for iron deficiency.
CLINICAL PEARL
342
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Serum iron can be normal in early iron deficiency. Anemia of chronic disease typically
has low serum iron but the ferritin is elevated or normal (not low).
Oral ferrous sulfate is the most common form of repletion. Reticulocytosis is the first
indication of response and peaks usually after 10 days of therapy. If the patient has severe
malabsorption and cannot be repleted orally, parenteral iron dextran can be given
intramuscularly or intravenously.
Follow-up Management and Prevention
CLINICAL PEARL
With unexplained iron-deficiency anemia in adults, always refer for colonoscopy to
exclude colon cancer.
Final Diagnosis
Iron-deficiency anemia
Ferrous sulfate orally (325 mg 3x/day) until hemoglobin level recovers
Repeat reticulocyte count in 2 wks
Repeat CBC in one month
Add oral vitamin C to increase iron absorption if cells are not being produced
343
344
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Case 8
Chief Complaint
“I have been bleeding for 2 days after cutting myself.”
History and Physical Examination
A 22-year-old man comes to the clinic for evaluation of abnormal bleeding after shaving.
This has been going on intermittently for years. It became very severe only after he took
aspirin this week—the first time in a long time. He has not had surgery in the past so he
cannot tell if there is increased bleeding.
Differential Diagnosis
Initial Management
Setting: outpatient
Diagnostic/Therapeutic Plan
Hemophilia A and B1.
Von Willebrand disease (vWD)2.
Immune thrombocytopenic purpura (ITP)3.
Factor XI deficiency4.
CBC
PT
345
Test Results
Assessment
Bleeding disorders should first be evaluated for whether they are from platelet or clotting
factor disorders. Platelet disorder-type bleeding is superficial, such as from the gums, gingiva,
epistaxis, or the skin. Vaginal bleeding is also from platelet disorders. The type of bleeding
cannot determine if there is a platelet defect in function or just a decrease in the number of
platelets.
Factor-type bleeding such as that from hemophilia is deep. Deep bleeding means into the joints
or into the muscles. Bleeding of the GI tract, urine or into the brain can be from either etiology.
All bleeding problems should always be evaluated with PT, aPTT, and CBC first.
The aPTT is elevated in vWD in about half of cases. This is because factor VIII antigen, which
is the von Willebrand factor, travels bound to factor VIII coagulant, which is the hemophilia
factor. It is very common that vWD presents with mild bleeding that is made worse after the
use of aspirin.
A type and cross is useful in almost any form of severe bleeding. You want to be sure you have
the ability to transfuse the patient, but you also want to show that you are thinking ahead. If this
aPTT
LFTs
Discontinue aspirin
Type and cross
CBC normal, including normal platelet count
PT normal
aPTT prolonged at 55 seconds
LFTs normal
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were a single best answer question, a type and cross would not be the most important thing to
do.
You will never get into trouble on a CCS case by showing you are thinking ahead to the
possibility of more severe bleeding. LFTs show that you know that clotting factors are made in
the liver.
CCS NOTE
On a CCS case, doing a type and cross shows that you understand what is needed in
advance for all potentially serious bleeding. On a type and cross, antibody testing is
also done, which shows you are looking at the possibility of antibody inhibitors.
Further Management Plan/Results
Decrease in VWF level
Abnormal
No significant change
CLINICAL PEARL
VWF or antigen level
VWF activity (ristocetin cofactor assay)
Repeat CBC
347
Always do a repeat CBC in any person with bleeding. It shows that you know the first
CBC will not show the ultimate blood count.
Discussion
All clotting factors are made in the liver with the exception of factor VIII and VWF. These
factors are made and stored underneath endothelial cells lining the vessel.
DDAVP causes the release of subendothelial stores of VWF and factor VIII. This is a safe way
to rapidly increase blood levels of VWF without the risk of transfusion. This will rapidly
increase the ‘stickiness’ of platelets. If DDAVP is not sufficient to stop bleeding, then factor
VIII replacement contains both VWF and factor VIII. This is also why you can use DDAVP for
mild hemophilia. Factor VIII antigen (the VWF) and factor VIII coagulant (the hemophilia
factor) travel bound to each other.
The bleeding time is of equivocal value. When you cut a person and there is a prolongation of
the bleeding time, this implies a defect in platelet function. It is not clear what the value is of
this test if you can do VWF antigen and activity.
Follow-up Management Plan
Final Diagnosis
Von Willebrand’s disease
Desmopressin (DDAVP)
Factor VIII replacement if this is not effective (rarely)
Avoid aspirin in the future
348
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349
Case 9
Chief Complaint
“How long do I have to stay in the hospital for my blood clot, doc?”
History and Physical Examination
A 57-year-old man is admitted for shortness of breath after developing a pulmonary
embolus. He has been administered IV unfractionated heparin for the last several days. On
hospital day 3 his platelet count has dropped from 185,000 mm
3
to 62,000 mm
3
but he is
otherwise improving. Warfarin (Coumadin) was started 2 days ago.
Physical examination reveals chest is clear to auscultation, cardiovascular exam is normal
with no murmurs or gallops. His extremities are normal.
Differential Diagnosis
Initial Management
Setting: inpatient hospital
Diagnostic/Therapeutic Plan
Heparin-induced thrombocytopenia (HIT)
1.
Immune thrombocytopenia (ITP)
2.
Thrombotic thrombocytopenic purpura (TTP)
3.
Hemolytic uremic syndrome (HUS)
4.
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