Thyroid UK

Thyrotropin-producing pituitary adenoma simultaneously existing with Graves' disease: a case report

One of the favourite expressions of doctors appears to be from this:

Zebra is the American medical slang for arriving at an exotic medical diagnosis when a more commonplace explanation is more likely. It is shorthand for the aphorism coined in the late 1940s by Dr. Theodore Woodward, professor at the University of Maryland School of Medicine, who instructed his medical interns: "When you hear hoofbeats, think of horses not zebras". Since horses are common in Maryland while zebras are relatively rare, logically one could confidently guess that an animal making hoofbeats is probably a horse. By 1960, the aphorism was widely known in medical circles.

(From Wiki.)

What would you make of a horse followed by a zebra?

The phrase worries me. It ends up appearing to suggest that rarity is a basis for exclusion from differential diagnosis.

Whereas we have seen the rare disease people pointing out that in total, there are vast numbers suffering from rare diseases, probably more than from the less rare ones.

Luckily for this patient, the doctors didn't ignore the numerous possibilities for hoofbeat generation - including donkeys, zebras and coconuts.

J Med Case Rep. 2017 Jan 6;11(1):9. doi: 10.1186/s13256-016-1172-4.

Thyrotropin-producing pituitary adenoma simultaneously existing with Graves' disease: a case report.

Arai N1, Inaba M2, Ichijyo T3, Kagami H2, Mine Y2.

Author information

1Department of Neurosurgery, Saiseikai Yokohamashi, Tobu Hospital, Yokohama, Japan.

2Department of Neurosurgery, Saiseikai Yokohamashi, Tobu Hospital, Yokohama, Japan.

3Department of Endocrinology and Metabolism, Saiseikai Yokohamashi, Tobu Hospital, Yokohama, Japan.



Thyrotropin-producing pituitary tumor is relatively rare. In particular, concurrent cases associated with Graves' disease are extremely rare and only nine cases have been reported so far. We describe a case of a thyrotropin-producing pituitary adenoma concomitant with Graves' disease, which was successfully treated.


A 40-year-old Japanese woman presented with mild signs of hyperthyroidism. She had positive anti-thyroid-stimulating hormone receptor antibody, anti-thyroglobulin antibody, and anti-thyroid peroxidase antibody. Her levels of serum thyroid-stimulating hormone, which ranged from low to normal in the presence of high levels of serum free thyroid hormones, were considered to be close to a state of syndrome of inappropriate secretion of thyroid-stimulating hormone. Magnetic resonance imaging showed a macropituitary tumor. The coexistence of thyrotropin-producing pituitary adenoma and Graves' disease was suspected. Initial therapy included anti-thyroid medication, which was immediately discontinued due to worsening symptoms. Subsequently, surgical therapy for the pituitary tumor was conducted, and her levels of free thyroid hormones, including the thyroid-stimulating hormone, became normal. On postoperative examination, her anti-thyroid-stimulating hormone receptor antibody levels decreased, and the anti-thyroglobulin antibody became negative. The coexistence of thyrotropin-producing pituitary adenoma and Graves' disease is rarely reported. The diagnosis of this condition is complicated, and the appropriate treatment strategy has not been clearly established.


This case suggests that physicians should consider the coexistence of thyrotropin-producing pituitary adenoma with Graves' disease in cases in which thyroid-stimulating hormone values range from low to normal in the presence of thyrotoxicosis, and the surgical treatment of thyrotropin-producing pituitary adenoma could be the first-line therapy in patients with both thyrotropin-producing pituitary adenoma and Graves' disease.


Endoscopy; Graves’ disease; Neurosurgery; Pituitary neoplasms; TSH-producing tumor; TSHoma; Thyrotropin

PMID: 28061802

DOI: 10.1186/s13256-016-1172-4

Happily, "Free full text" is available here:


4 Replies

Those of us who have Cushing's disease have the zebra as our symbol. Cushing's is considered to be a rare condition which is hard to diagnose. however I think the reality is that doctors are not prepared to consider it as they think it is rare. I host a group for people being tested or diagnosed with Cushing's, it only started 6 months a go & we have over 245 UK members, so not that rare! It is interesting to see that there are groups of us in several areas which seems to suggest that the Endo's in that area are prepared to look at rare conditions rather than dismissing them outright.


Based on 2 in a million per year[1], we would expect about 128 new cases a year in the UK. That is, of course, quite rare but, as with so many disorders, definition and diagnosis work (or fail to work) with each other to produce potentially many more cases.

As you have held back from self-promoting, maybe you would care to post a link to your group, if you have an online presence?



If that's ok? Shall I do it in a new post?


Hadn't been expecting that question! Why not? If you were one of the people pushing their site all the time, that would be another matter. :-)

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