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Learning Center
Coagulation Corner
Sunday, January 3, 2010
Coagulation laboratory and the horrible, no good day!
Ever hear of the book Alexander and the Horrible No Good Day- If you have children I am sure you have read it- if not it basically goes through a day of a child that just gets worse and worse. The adult version would be oversleep, car needs gas, working with a short staff, sitting in traffic, and of course ending the day with that school project that your child has had for the past month-
Everyone has had those days, but what about in the laboratory? You know those days, controls don't work, reagents are expired, new standard curves need to be made, something is always blinking or beeping. One of my worst days ended up providing me with one of my favorite case studies-
If was a Friday afternoon (no surprise there) and I was fairly new in my position as a technical specialist. My director said, I am leaving, you are in charge, okay now if that isn't a prescription for disaster I don't know what is-
Around 2pm we received a sample from the ED on a 12 year old boy with the diagnosis of hematuria for a PT and an aPTT. The results were as follows:
PT= 35 sec (10.5-13.5 sec)
aPTT= 107 sec (24.5-35.5 sec)
So we had a patient who was bleeding, with prolonged screening tests.
Since the results were critical the physician was contacted and he requested that we add a fibrinogen and a D-dimer (the only d-dimer available in the laboratory was the latex agglutination) results were as follows:
Fibrinogen = 256 mg/dL (150-400mg/dL)
D-dimer = <0.5ug/ml - negative
These were added on to determine if the patient was in DIC (disseminated intravascular coagulation). To complete the picture, we looked up the platelet count which was 30,000- so was this DIC? Both the D-dimer and Fibrinogen was normal, which made it unlikely, but what about the process by which platelets are consumed in DIC? We asked for additional information, and discovered that this boy was a patient that had a history of Idiopathic Thrombocytopenic Purpura (ITP), so the platelets could not be used as a discriminator for DIC. (well so much for leaving on time on a Friday!) Additional studies needed to be performed, in the interest of time a mixing study and factor assays were ordered. A resident was contacted to get us as much information as possible. The following additional information was provided.
12 year old boy with a history of ITP, presented with hematuria,
The patient also had a cold and been taken OTC cold medication.
Had a swollen ankle from a fall off a bike the previous day.
He had previously been on nasal steroids as treatment for his ITP,
But currently was doing well and the pediatrician had removed him from the steroids.
So, was the hematuria a result of ITP? ITP presents with mucosal bleeding so this type was not characteristic of ITP, also the platelet count was fairly good for an ITP patient.
Additional testing was as follows:
Mixing study: 1:1 mix= (not incubated)
PT = 35 sec
Pooled Normal Plasma = 11.1
1:1 mix = 36 sec
aPTT= 107 sec
Pooled Normal Plasma = 34.2
1:1 mix = 111 sec
Now, no matter what "rules" you use to determine if a mixing study has corrected, it is safe to say these results show an uncorrected mix which is suggestive of an inhibitor. Since neither test corrected, the inhibitor would be in the common pathway (I, II, V and X). Now was a time to panic, remember I was in charge-
An inhibitor to a specific factor must be diagnosed quickly, and treated. One thing was for certain the patient was already bleeding, and factor specific inhibitors cause bleeding that needs to be controlled. Also, a Bethesda titer should be performed to determine the strength of the inhibitor. A Bethesda titer is performed against whatever factor is determined to be inhibited. This measures the amount of inhibition present in 50% of the factor and is measured in Bethesda Units (BU). The greater the BU the higher the inhibitor.
At this rate, I was going to be lucky to have even a Saturday!
We went ahead to look at the common pathway factors, I, II, V and X- well we knew that I or fibrinogen was normal- factor V, and X were low 56% and 45% respectively, and factor II was undetectable. At that point I knew what the problem was, but remember we can't order or add on tests in the laboratory, and I was new in my position, so now I had to call the physician. Luckily I worked with really smart pediatric hematologists, who quickly suggested that I perform a Dilute Russel Viper Venom- which was very positive- Outcome this patient had a very strong Lupus Anticoagulant- but wait, people with LA, don't bleed they are at a risk for thrombosis- however- there are several instances in which Lupus patients can bleed-
1. Due to a qualitative or quantitative deficiency of platelets
2. Due to an incomplete abortion
3. And due to the consumption of prothrombin- which was the case of our patient, hence the undetectable factor II.
This was causing the hematuria, and do you remember the swollen ankle, which was determined as a result of a fall off a bike? Ha, that ended up to be a blood clot. Why would this manifest itself now? How come it wasn't previously? The patient had been on nasal steroids against ITP-this was also suppressing the LA,
It wasn't until he had been removed from the steroids that the LA manifested itself. So which came first the ITP or the LA? And what is the deal with the consumption of Factor II?
The estimated prevalence of inherited prothrombin deficiency worldwide is 1 per 2,000,000 population. The prevalence is higher where consanguinity is common. In parts of the world where vitamin K is not routinely administered in the neonatal period, hypoprothrombinemia secondary to vitamin K deficiency is relatively common. The incidence of hemorrhagic disease of the newborn in the absence of active prophylaxis is about 1 in 500 newborns.
Patients with hypoprothrombinemia lupus anticoagulant syndrome (HLAS) may have other symptoms of autoimmune disease. (In this case ITP) As an alternative, they may have a history of a preceding viral infection, usually an upper respiratory infection ( there is another clue!) or gastroenteritis.
HLAS is characterized by a very strong LA and polyspecific antibodies. They bind the epitopes of the anionic phospholipids and of prothrombin, but they do not neutralize prothrombin. The FII activity deficiency is not due to an inhibitor, as suspected, but to an evident factor decrease owing to the higher clearance of the prothrombin-antibody complex in the reticuloendothelial system.
And so ended a very long day, with a very engaged staff going step by step through a very interesting case. There were no breaks, no lunches and everyone left late, but they all will never forget the laboratories horrible, no good, very bad day- and how they helped this little boy, no parent will every know, nor will it be put in a journal, but they all know- and they will never forget it. They even all came back on Monday!
Happy 2010-
May your platelets be sticky when needed,
And your factors stay in balance!
Health and Happiness to all-
Donna Castellone
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About the Author
Donna Castellone,
MS, MT(ASCP)SH
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