Thalessemia minor and aviation

Hi everyone, I have recently joined this forum as i found it highly informative.  However I have a specifci querry and that concerns the link between thalessemia minor and military aviation.  I have been aviating since the last 21 years and all these years probably my Hb count was above 13 but recently my Hb count came as 10.5 and I was diagonosed with Beta Thalessemia minor.  They say that I can continue in aviation as long as my Hb stays above 11.5. My question is that " is there any scientific backing to this figureof 11.5"

Hi Tango,

I've seen this mentioned before but have never seen a good explanation as to why this would disqualify someone from flying.

This is from the US Navy's guidelines. It may take a few seconds for the page to load.
http://www.med.navy.mil/sites/navmedmpte/nomi/nami/arwg/Documents/Waiver%20Guide%20-%20Hematology.pdf

8.5 THALASSEMIAS
AEROMEDICAL CONCERNS: Thalassemias produce a low-grade anemia that can cause problems at altitude. Splenic enlargement and worsening of the anemia can occur under conditions of stress.
WAIVER: Aviation personnel must meet the hematocrit standards previously listed in the Anemia section (section 8.1). Personnel with beta thalassemia minor (heterozygous carriers – beta thalassemia trait) or with alpha thalassemia minor (1 or 2 gene loci absent) may be considered for waiver provided there are no other hemoglobinopathies present. Any anemia must be limited to a mild, microcytic anemia. Patients who have required splenectomy because of their thalassemia are permanently disqualified from military flying.
INFORMATION REQUIRED:
1. Establishment of the detailed diagnosis
a. Estimation of HbA2, HbF, serum Fe and ferritin and by quantitative electrophoresis
2. Focused physical exam
3. Internal medicine or hematology consult (if obtained)
NOTE: The diagnosis of thalassemia cannot reliably be made in the face of iron deficiency, hence iron studies must be provided that document normal iron status with submission of the waiver request.
TREATMENT: N/A.
DISCUSSION: The thalassemias probably constitute the world's largest genetic disorder. Beta thalassemia occurs widely in a belt extending from Southeast Asia, through India, the Middle East, the Mediterranean (as far north as Romania and Yugoslavia), and to north and west Africa. Carrier frequencies can vary from 2 to 30% in these populations. Beta thalassemia also occurs sporadically in all racial groups. Splenectomy results in a greater risk of overwhelming infection and of severe malaria, which can affect an aviator’s fitness to deploy. The flight surgeon will often make the diagnosis of thalassemia after chart review turns up a chronic, low grade microcytic anemia that does not respond to iron therapy. Patients with homozygous beta thalassemia or deletions in more than two of the alfa chains are almost always severely symptomatic or anemic, and as such rarely make it into the military.
ICD-9 CODE:
282 Thalassemias

There may be no way around the military guidelines, regardless of whether or not the altitude would actually have any effect on your oxygen state.

However, you have had a normal hemoglobin level for years and have had a somewhat sudden drop in your level. I would ask why. Hemoglobin levels tend to stay fairly steady, but yours has inexplicably dropped 2.5 points. My first question has to be have you been exposed to any solvent type chemicals during the period when your Hb level dropped? Chemicals like benzene and naphthalene can cause sudden hemolysis, the destruction of red blood cells. We also have a list of foods and drugs that can cause hemolysis at http://www.thalassemiapatientsandfriends.com/index.php?topic=3410.msg34830#msg34830
Although this is more common with alpha thal, when there is a significant and unexplained drop in Hb level, I suggest reviewing this list to see if there may be an explanation for the drop.

If you suspect a slow but steady drop in Hb, then another approach may be needed to try to raise your Hb level back up. Supplements that may have a positive effect on Hb level are folic acid, B Complex, magnesium, vitamin E (natural), wheatgrass tablets and resveratrol. One other note I will make is that if you have been living at a high altitude and then moved to a lower altitude, you will also see a drop in Hb level. There is nothing that can be done about this, as higher altitudes stimulate an adjustment by the body to compensate for the lack of oxygen at high altitude, and a higher Hb level will become apparent after 3 or more weeks at high altitude. So, if you relocated from someplace like Denver to a low altitude, you would see a measurable drop in Hb level after a few weeks.

And to answer your question, I seriously doubt that this arbitrary Hb cut-off level is based on science. Thal minors fly all the time without incident. Keep in mind that there are literally hundreds of millions of thal minors on earth and most are undiagnosed, so obviously minors do fly regularly. However, since the military is testing the Hb levels, low Hb's will stand out and the precaution is taken, regardless of the individual health of the subject. (A note where sickle cell anemia is involved. Sickle cell trait does create a different set of problems at altitude and great caution is recommended).

Thanx Andy for the exhaustive and informative inputs.  You see, I think I am not iron deficient as my Serum ferritin count is 78.9, the other associated values are MCV-74.8, MCH-24.5 and PCV-32.5. The RBC count is 4.3.
The other issue which I find difficult to digest is that since the permissible Hb range for lady pilots is 11.5 - 16.0g/dl; what happens to those with a thalassemic trait coz they would never touch 11.5 (which is there normal value)

Hi Tango,

Sudden iron deficiency without a known blood loss is uncommon, so I didn't even consider the possibility, because your Hb has regularly been at a non-anemic level. And, we know that iron has no positive effect on anemia that isn't caused by low iron, so unless there is some chance of un-diagnosed bleeding, I believe an approach that provides the necessary component to build red blood cells is more likely to yield results. One thing I didn't mention is vitamin D. If you're not getting regular exposure to the sun, you might want to consider have your D level checked. A level under 30 should be corrected with supplements. D has an effect on almost everything in the body and has long been the most overlooked nutrient.

If you work at it, you may be able to get your Hb up enough to reach 11.5 (it is a somewhat arbitrary figure and I have seen the "normal" level vary according to the source). I do have to mention that the anecdotal evidence collected here does show that many minors develop problems as they age, so this is possibly related to age. However, assuring that you are getting proper nutrition can help to combat the effects of age, and also keep energy levels higher. I am also wondering if you can show that there have been no other problems associated with anemia, if a waiver of the rule may be granted. The stated acceptable low Hb of 11.5 does not tell the whole story. Each person is different and many thal minors with an Hb in your current range, show very few if any problems from thalassemia. Also, if there is any doubt, have a hemoglobin electrophoresis test done if it hasn't already been run. This will confirm thal carrier status.

I want to add another document where US Army Aviation clearly tells about "no problem' with thal minor... i think this is the smartest approach i have ever seen from any institute or establishment towards thal trait people.

"USAARL Report No. 96-15
...
                                         Exception to policy process
U.S. Army aviator candidates will not enter flight training with a medical disqualification.
They are not eligible for waivers for the medical disqualification. Entrance into U.S. Army aviator
training programs with a medical disqualification requires an ETP issued by aeromedical waiver
authorities at the Department of the Army or National Guard Bureau. ETPs are granted only to
commissioned officer candidates by regulation, though historically, many are granted to warrant
officer candidates. ETPs are granted only to exceptional officers with minor, static medical
disqualifications. ETPs are not likely to be recommended for disqualifying conditions that are
dynamic and may progress with time, are prone to recurrence or exacerbation with military and/or
aviation duties, or affect aviation safety and operations. ...


Exception to policy case histories

... A male applicant to Army aviator training had a hematocrit ranging from 37 to 39 percent
on multiple measurements. The standard is that a hematocrit is disqualifying if it is below 40
percent. A diagnosis of mild normochromic, norrnocytic anemia due to beta thalassemia minor was
made following an evaluation. The applicant requested an exception to policy. USAAMC
recommended an exception to policy since the condition was minor, stable, and not subject to
exacerbation in the operational aviation environment. The waiver authority granted the exception
to policy. He entered flight training. Followup examination showed the hematocrit remained stable.
After a series of similar cases, USAAMC changed the regulation so that minor deviations of
hematocrit due to beta thalassemia minor were no longer disqualifying for Army aviation service. ...
"
www.usaarl.army.mil/TechReports/96-15.PDF

Do you have a link to the US Army recommendations? I think it would be helpful for others to be able to cite.

Hi Andy,
I have provided the link later... if that doesn't open for any reason here is the attachment

I wanted to confirm if a Serum ferritin count of 78.9 is normal or on the lower side

http://www.clinlabnavigator.com/Test-Interpretations/ferritin.html?letter=F

Reference range is 20 300 ng/mL in men and 20 200 ng/mL in women.

It's well within normal range.