Page 15 - Journal of Special Operations Medicine - Winter 2015

form of follow-up. Lee et al. have suggested that clini- Additionally, levels of fat-soluble vitamins should be
cal judgment is paramount in following patients with evaluated and increased as necessary.
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heterozygous FHBL. Given the potential for progres-
sion of hepatic steatosis to cirrhosis and liver failure, The neurologic manifestations include cerebellar dys-
6
monitoring liver enzymes as a marker for hepatic ste- function marked by ataxia and dysmetria. Addition-
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atosis is reasonable. This may be particularly impor- ally, compromise of posterior column function with
tant in patients with other risk factors for fatty liver, loss of proprioception and deep tendon reflexes (DTRs)
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such as diabetes or the metabolic syndrome. Addi- can be seen. These patients must have a thorough neu-
tionally, monitoring levels of fat-soluble vitamins also rologic examination without evidence, even subtle, of
seems appropriate. This may be particularly important pathology. The development of neurologic sequelae is
in patients with known steatorrhea. While much more not likely to be acute in onset, but rather gradual, and
likely in the other HBLs, there is at least one report in progressive as levels of fat-soluble vitamins decrease,
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the literature of ocular pathology in a patient with het- leading to deleterious effects on spinocerebellar axons.
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erozygous HBL. As such, a baseline retinal examina- This is not likely to manifest suddenly during covert
tion may be appropriate, with further examinations as operations.
clinically indicated.
Also, these neurologic findings should not interfere with
the diagnosis of diving-related injuries, including type II
Relevance to Diving and Special Operations
decompression sickness or arterial gas embolism (AGE),
To the authors’ knowledge, FHBL has never been in- as both have a much more acute onset. The neurologic
vestigated from the perspective of clearance for Special findings in AGE would not include loss of DTRs, but
Operations duty. The relative prevalence of the hetero- rather hyperreflexia as the upper motor neurons are de-
zygous state of the disease is high enough that military prived of oxygen.
recruits found to have low lipids while undergoing rou-
tine screening for Special Operations are likely to be Of note, much more common in heterozygous FHBL is
encountered. How did we approach our patient who steatorrhea. Symptoms may include bloating and diar-
presented with low lipids and in whom we thought rhea. This may not be compatible with Special Opera-
a presumptive diagnosis of heterozygous FHBL was tions duty if it interferes with the reliable performance
appropriate? What are some specific considerations of duties. In addition to assessment of fecal fat content,
needed for this population, and what studies should be these patients must be questioned as to the frequency
obtained prior to clearing patients to train in Special and severity of symptoms.
Operations?
Special Operations Candidate
Special Operations in the military require a high degree
of reliability and physiologic performance. The poten- In our patient with a lipid profile and medical history
tial for complications from disease states should be se- suggestive of heterozygous FHBL in whom genetic test-
riously considered. The most concerning complications ing was not feasible, we thought the following workup
are ophthalmologic and neurologic. Pathology is much was sufficient to clear him for Special Operations duty.
more likely to develop in ABL, CRD, and homozygous Secondary causes were ruled out primarily by history.
FHBL; however, the potential for devastating results in Specifically, it was noted that he was not a vegetarian,
this population force the provider to ensure that there is he had no evidence of acute or chronic illness, and he
no evidence of disease, even when the diagnosis is pre- had no abdominal pain or food intolerance to suggest
sumed to be heterozygous FHBL. sprue, irritable bowel disease, or pancreatitis. In addi-
tion, his complete blood cell count and thyroid-stimu-
The development of ophthalmologic symptoms could be lating hormone levels were normal. Levels of fat-soluble
detrimental to both mission and warrior. Our Special vitamins were obtained and were all within normal lim-
Operations Forces operate in austere environments, fre- its. Because the most frequently reported pathologic de-
quently using the cover of darkness. Decreased night vi- velopment in heterozygous FHBL is related to the liver,
sion is often the first symptom reported in patients with the patient’s liver enzyme levels were measured and
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hypolipidemia who develop vision symptoms. Other found to be normal. With normal liver enzyme levels,
complications, while uncommon, are due to vitamin A the suspicion that he had any significant hepatic steato-
and E deficiencies and include ptosis, ophthalmoplegia, sis was low. However, this was confirmed with a liver
and corneal ulcers. While these symptoms are unlikely ultrasound, which was normal. He did report a his-
to develop in heterozygous FHBL, it seems reasonable tory of somewhat frequent bowel movements, so fecal
to have a retinal examination by an ophthalmologist or fat content was obtained and was found to be mildly
optometrist to ensure the absence of subclinical disease. elevated (8.3g/d [reference range, 0–7g/d]). Because he

Hypolipidemia: Case Report and Review 3