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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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Organ system–specific consultations should be requested for complex cases. Do not
worry if the consultant doesn’t offer advice; it still shows that you know when to ask
for assistance.
The myopathy described in the patient here is proximal myopathy, which is the most common
myopathy in Grave’s and in all thyroid disease.
Final Diagnosis
Grave’s disease
Plummer’s disease patients have long-standing multinodular goiters which become
thyrotoxic later.
Toxic multinodular goiter patients have a hyperfunctioning solitary nodule, which is not
present in this patient.
Subacute thyroiditis patients have diffuse thyromegaly like our patient, but the thyroid is
tender. Subacute thyroiditis patients are differentiated by their short duration of symptoms
and low 24-hour radioactive iodine uptake (usually <5%).
441
Case 6
Chief Complaint
“I feel thirsty, and I’m urinating a lot.”
History and Physical Examination
A 56-year-old woman with no past medical history comes to your office complaining of
polyuria and polydipsia of 4 days duration. She denies dysuria and has no fever or chills.
She also admits to a 13-lb weight gain, severe fatigue and depression for the past 4
months. Her skin has also been bruising easily. She denies shortness of breath or chest
pain. She takes no medications.
On exam she is afebrile. Her blood pressure is 160/98 mm Hg, pulse 78/min, and
respirations 14/min. She is obese and her face is remarkably round and ruddy. There are
several purple striae over the abdomen and the thighs. Heart and lung examinations are
WNL. Neurologic examination reveals mild bilateral upper extremity weakness. There is
mild edema of the lower extremities.
CCS NOTE
Do not administer emergency therapy to lower BP unless there are symptoms such as
shortness of breath, blurred vision, chest pain, or confusion. This patient’s BP does not
need urgent therapy because the symptoms are unrelated to it.
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Differential Diagnosis
Initial Management
Setting: outpatient work-up and treatment
Diagnostic/Therapeutic Plan
Cushing’s syndrome1.
Due to prolonged exposure to supraphysiologic levels of cortisol; patients typically
have truncal obesity, moon facies, violaceous striae, new onset DM, and
hypertension; this patient’s presentation strongly suggests hypercortisolism
—
Hypothyroidism2.
Characterized by many of the symptoms this patient displays, including weight gain,
fatigue and depression
—
New onset DM3.
Obesity, polyuria and polydipsia suggest diabetes; however, DM does not present
with skin bruising
—
Glucose level, electrolytes, kidney function, calcium
CBC
TSH
Hemoglobin A1c
24-h urine free cortisol excretion
Overnight 1-mg dexamethasone suppression test
Midnight salivary cortisol measurement
Plasma ACTH
MRI pituitary gland
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Test Results
Assessment
The patient presents with symptoms suggestive of a hypercortisolism. Clinical features include:
These symptoms and signs are all suggestive of Cushing’s syndrome. The diagnostic work up
aims to confirm excess cortisol production. There are 3 tests that can confirm the presence of
excess cortisol:
Glucose: 356 mg/dL, sodium: 138 mEq/L, potassium: 3.1 mEq/L, chloride: 95 mEq/L,
bicarbonate: 34 mEq/L, BUN: 13 mg/dL, creatinine: 0.7 mg/dL, calcium: 9.8 mg/dL
CBC: normal
TSH: normal
Hemoglobin A1c 8.1%
24-h free cortisol secretion: 650 ug/24 hr (normal: <200 ug/24 hr) elevated
Overnight dexamethasone suppression test: 28 µg/dL (normal: <5 µg/dL) non-supressable
Midnight salivary cortisol measurement: 24 nmol/mL (normal <4 nmol/L) elevated
Plasma ACTH: 18 mg/L (normal <5ng/L)
Truncal obesity
Moon facies (round-shaped face)
Dorsocervical fat pad (buffalo hump)
Skin changes such as straie, acne, and bruising
Osteopenia
Neuropsychiatric symptoms (emotional lability, depression, psychosis)
Menstrual irregularities
Impotence
Possible new onset DM and hypertension as well
24-h urine free cortisol
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It is recommended that if one test is abnormal, a second test be performed to confirm the
diagnosis.
This patient has an abnormal result on all 3 tests, which confirm the diagnosis of Cushing’s.
The next step is to measure plasma ACTH levels, which will differentiate ACTH-dependent
hypercortisolism from ACTH-independent hypercortisolism.
The electrolyte abnormalities seen in Cushing’s syndrome are secondary to increased
mineralocorticoid activity that act to increase the secretion of potassium and H+ in the kidney.
This results in hypokalemia and a metabolic alkalosis.
It is important to rule other causes for the patient’s symptoms such as hypothyroidism by
measuring a TSH level. Additionally, it is not unreasonable to check a CBC if the patient
presents with easy bruising. These test results were normal in the current scenario.
CLINICAL PEARL
Cushing’s syndrome refers to a state of hypercortisolism. However, if a pituitary
microadenoma is the cause of the hypercortisolism, the diagnosis is referred to as
Cushing’s disease.
Midnight salivary cortisol measurement
Overnight low-dose dexamethasone suppression
If ACTH is elevated as it is here, do an MRI of the sella turcica to confirm the presence on
an adenoma. ACTH can also be secreted ectopically (associated with small cell carcinoma
of the lung; paraneoplastic syndrome).
If ACTH is decreased, that would indicate a possible adenoma in the adrenal gland itself,
which directly produces cortisol.
445
Basic Science Correlate
The clinical features of Cushing’s syndrome are due to excess cortisol. ACTH
stimulates the adrenal gland (mostly in the zona fasciculata) to convert cholesterol into
cortisol via a series of enzymatic reactions. Cortisol enhances hepatic gluconeogenesis
which produces hyperglycemia. In turn, increased serum glucose causes insulin
secretion from the pancreas. Insulin acts to increase the storage of fat in the adipose
tissue causing weight gain and obesity.
The muscle weakness seen in this patient is due to muscle breakdown via cortisol.
Amino acids that are derived from the breakdown of muscle are used to supply the
liver with the substrates for gluconeogenesis. The muscle breakdown also thins the
extremities in these patients.
Another key sign of excess cortisol production is hypertension, due to an increase in
production of weak mineralocorticoids. Mineralocorticoids retain sodium in the
kidney, and thus passive reabsorption of water, which acts to increase the effective
circulating blood volume and thus increase BP. Additionally, mineralocorticoids act
in the kidney to enhance potassium and H+ secretion causing the classic electrolyte
abnormalities that are often observed. Of note, aldosterone production requires
angiotensin II activity which is not affected by increased ACTH. Therefore,
aldosterone itself is not increased.
Cortisol secretion normally exhibits a diurnal rhythm. This means that there is a
peak and trough of serum cortisol levels every 24 hrs. Typically, cortisol levels
reach their peak early in the morning, and a trough late at night. In Cushing’s there is
no diurnal rhythm because cortisol levels are persistently high. Salivary cortisol is
in equilibrium with free cortisol levels; therefore, a late night salivary cortisol level
will be elevated in Cushing’s and can be diagnostically useful.
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Further Diagnostic Plan/Results
Serum ACTH level Elevated
High-dose dexamethasone 4 μg/dL (suppressed)
MRI of the pituitary Positive for microadenoma
Further Management Plan
The management for Cushing’s disease should include an endocrinology consult.
CCS NOTE
Normal values for diagnostic results are provided in the case simulations. You do not
need to memorize them.
Treatment for an ACTH-secreting adenoma is surgical excision. The surgery may be
performed transsphenoidally. After surgery, patients are often deficient in ACTH. Therefore
they may require glucocorticoid replacement for up to a year after the removal of the tumor.
Patients may also experience residual disease if the tumor was not completely excised. In
this case, stereotactic radiosurgery might be indicated.
Secondary DM and hypertension usually resolve once the underlying cause of the Cushing’s
syndrome is treated, though a short course of treatment may be necessary to control
excessively high BP or glucose levels.
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Discussion
The patient in this case presents with signs and symptoms of Cushing’s syndrome. The most
common cause of Cushing’s syndrome is a pituitary adenoma which overproduces ACTH
(Cushing’s disease). Resultant excess cortisol production produces a wide variety of clinical
symptoms. Importantly, Cushing’s syndrome is a cause of both secondary DM and hypertension.
Diagnosis of Cushing’s syndrome should begin with tests to identify excess cortisol levels. If
any of the 3 initial tests are abnormal, a second confirmatory test should be performed. Once
hypercortisolism is established, a search for the underlying cause is conducted.
In this case the patient was noted to have a pituitary adenoma on MRI. The appropriate
treatment will be surgical resection. In cases where a pituitary adenoma is not the cause of
excess cortisol production, one must conduct a search for either ectopic ACTH production or a
cortisol-producing adrenal adenoma. If ACTH levels are low, perform a CT scan of the
adrenal glands to identify a cortisol-producing adenoma. Small cell carcinoma of the lung can
produce a paraneoplastic syndrome in which ectopic ACTH is produced.
Follow-up Management and Prevention
After the underlying cause of the Cushing’s syndrome is treated, the patient should continue to
be monitored. The patient should have regular BP checks and follow up labs (hemoglobin A1c,
electrolytes, glucose levels). A lipid profile should also be monitored. Temporary
pharmacologic treatment of BP and diabetes may be necessary. Additionally, even though the
DM in this patient was secondary to another condition, there is still risk for the macrovascular
and microvascular complications of DM. Patients also need assessment for
osteopenia/osteoporosis with a bone density scan.
Final Diagnosis
Cushing’s disease
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449
Case 7
Chief Complaint
Headache and palpitations
History and Physical Examination
A 33-year-old woman comes to the office for evaluation of several hours of severe
headache, flushing, and palpitations. She recalls several similar episodes in the past, but
her symptoms were less severe and of shorter duration. Each of these episodes occurred
after going to the bathroom. Her past medical history is significant only for a long history
of migraine headaches, which are difficult to control.
She is diaphoretic and anxious-appearing. Her T is 37.0 C (98.6 F), BP is 195/110 mm
Hg, respirations are 20/min, and pulse is 138/min. Orthostasis is elicited. Her head, eyes,
ears, nose, and throat are unremarkable. Her heart is tachycardiac with normal heart
sounds. Her lungs are clear to auscultation, abdomen is benign, and extremities are
unremarkable.
Differential Diagnosis
Pheochromocytoma
1.
Primary aldosteronism
2.
Renal artery stenosis
3.
Essential hypertension
4.
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