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Endocrine > Cushing syndrome > Flashcards

Cushing syndrome Flashcards

1
Q

What is the definition of Cushing’s syndrome?

A

Cushing’s Syndrome is the clinical state produced by chronic glucocorticoid excess

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2
Q

What is the definition of Cushing’s Disease?

A

Cushing’s Disease is Cushing’s syndrome caused by bilateral adrenal hyperplasia from an ACTH secreting pituitary adenoma (usually a microadenoma)

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3
Q

What is Nelson’s syndrome?

A

Occurs post bilateral adrenalectomy resulting in unsuppressed ACTH production

This results in

1) Macroadenomas of the pituitary to inc ACTH production 🡪 mass effects
- visual disturbances (due to compression on optic chiasm)
- headaches (due to infiltration into bony structures / meninges)
2) Excessive ACTH =
- ↑ beta-MSH and ACTH
- hyper-pigmentation of the skin

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4
Q

What are the causes of ACTH independent Cushings?

A

Adrenal adenoma, carcinoma or Bilateral adrenal hyperplasia (i.e. Primary Hypercortisolism)

Iatrogenic (99%): Steroids, TCM, Jammu

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5
Q

What are the causes of ACTH dependent Cushings?

A

Pituitary disease (Cushing’s disease)

  • Adenoma
  • Hyperplasia

Ectopic ACTH

  • Small cell lung carcinoma (can also produce PTHrP)
  • Carcinoid tumour

Ectopic CRH
- Medullary Thyroid carcinoma

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6
Q

What are the signs suggesting suggesting adrenal carcinoma as underlying cause of Cushing?

A
  • Palpable abdominal mass
  • Signs of virilisation in females: acne & hirsutism (since carcinoma will not only increase cortisol production but also androgen production)
  • Gynaecomastia in males
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7
Q

What are the signs suggesting suggesting ectopic ACTH production as underlying cause of Cushing?

A

Ectopic ACTH tumors tend to be more aggressive, releasing more cortisol with lesser time for physical changes to occur

  • Absence of Cushingoid body habitus unless tumour has been slow growing and allowed time for Cushingoid features to develop
  • More prominent oedema and hypertension
  • More severe muscle weakness from hypokalaemia
  • History usually of more rapid onset of symptoms and signs
  • Pigmentation (only in ACTH dependent)
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8
Q

What are the presenting complications of someone with Cushing’s?

A

Increase appetite and weight

Skin changes

Change in appearance

Metabolic Syndrome: DM, HTN, HLD

Hypokalaemia due to mineralocorticoid effect: Arrhythmia, Weakness

Muscle weakness (Proximal myopathy)

Osteoporosis: Any recent #, bone pain / spine pain

Poor Immune system: recurrent illnesses

Mood changes (depression, lethargy, irritability, psychosis): Result of cortisol’s effect in the degradation of hippocampus

Sleep disturbances

Erectile dysfunction (men) or amenorrhea & hirsutism (women)

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9
Q

What are the skin changes in a patient with Cushing’s?

A
  • Acanthosis nigricans from IR (areas of dark, velvety discoloration in body folds and creases)
  • Easy bruising
  • Acne, hirsutism
  • Purple striae typically on abdomen
  • Hyperpigmentation (only in ACTH dependent cushing’s)
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10
Q

What are the changes in appearance in a patient with Cushing’s?

A
  • Rounded countenance, moon-like facies, lemon on sticks appearance
  • Supraclavicular fat pad & dorsocervical fat pad (Buffalo Hump)
  • Facial plethora
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11
Q

Why will a patient with Cushing’s have muscle weakness?

A

Due to catabolic effect of cortisol

Also due to hypoK which causes muscle weakness

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12
Q

What hx would you ask to elucidate aetiology of cushing syndrome?

A

Use of any exogenous steroids / TCM

Any S&S of

  • Lung Ca
  • GI Ca, Carcinoid Syndrome

Central

  • Hyperpigmentation;
  • Mass effect in pituitary – BOV, Headache. Rare B/c most ACTH-producing adenomas are MICROADENOMAS <1cm

Past Medical History/Drugs

  • Previous history of endocrine condition
  • History of hypertension, diabetes
  • Any current treatment with long-term steroids?
  • Any TCMs/Jammu?

Family History
- Family history of any pituitary tumours?

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13
Q

What signs to look out for in the upper limbs when examining a patient with Cushing’s?

A

Thin arms (Lemon on sticks)

Fingers for etiological clues

  • Clubbing, tar staining (lung cancer)
  • Joint deformities in RA, SLE (exogenous steroid use)
  • Rashes: dermatomyositis, psoriasis, SLE

Skinfold thickness on the backs of hands (double pinch test – pinch pt’s skin & your own)

Bruising

Proximal myopathy

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14
Q

What signs to look out for in the face when examining a patient with Cushing’s?

A
  • Conjunctival pallor (BGIT from steroid)
  • Cataracts
  • Acne & Hirsutism
  • Telangiectasia (small dilated vessels near skin surface/mucous membranes)
  • Plethora (red, florid condition: ensure absence of polycythemia)
  • Moon-like facies (use “Rounded countenance” instead in the presence of patient)
  • Oral thrush
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15
Q

What signs to look out for in the neck when examining a patient with Cushing’s?

A
  • Acanthosis nigricans
  • Supraclavicular fat pads
  • Dorsocervical fat pad (Buffalo hump)
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16
Q

What signs to look out for in the trunk when examining a patient with Cushing’s?

A
  • Central obesity
  • Purple striae
  • Palpate for bony tenderness of vertebral bodies (crush fractures from osteoporosis: steroid anti-Vitamin D effect and increased urinary Ca2+ loss)
  • Hepatomegaly (fat deposition, adrenal carcinoma deposits)
17
Q

What signs to look out for in the lower limbs when examining a patient with Cushing’s?

A
  • Proximal myopathy
  • Bruising
  • Poor wound healing
  • Palpate for oedema (salt and water retention)
18
Q

What are examinations to perform in a patient with Cushing’s?

A

Blood pressure

Urine dipstick (glycosuria)

Respiratory examination (lung cancer, ILD, asthma)

Abdo Exam for adrenal masses (adrenal carcinoma palpable over renal area)

Visual field testing

  • Bitemporal hemianopia in pituitary tumour
  • Not likely in Cushing’s because it is usually a microadenoma)

Fundoscopy (optic atrophy, hypertensive, diabetic changes)

19
Q

What is the workup for exogenous steroid use?

A

Paired ACTH / SST (Short Synacthen Test)

  • Stop steroid / TCM for up to 2 weeks (if outpatient) before Synacthen
  • IM/IV Synacthen (250mcg) given & Cortisol measured at 0th (8am), 30th, 60th min
  • 0th min: 8am cortisol <250nmol/L due to chronic
  • 30th/ 60th min: suboptimal rise in cortisol (normal- cortisol DOUBLES AND > 500nmol/L )
20
Q

When doing short synacthen test, SST: 200 🡪 220 🡪 250; ACTH high (normal <10.1Umol/L). What are the differential diagnoses?

A

Acute Primary hypocortisolism: Due to acute dysfunction 🡪 there is loss of adrenal function = suboptimal rise

Eg: Acute adrenal hemorrhage

  • APS (Antiphospholipid Syndrome) from SLE
  • Waterhouse-Friderichsen Syndrome (from meningococcemia)
21
Q

When doing short synacthen test, SST: 50 🡪 60 🡪 70; ACTH high (normal <10.1Umol/L). What are the differential diagnoses?

A

Due to chronic dysfunction 🡪 there is loss of adrenal function = suboptimal rise

Eg: Addison’s

22
Q

When doing short synacthen test, 50 🡪 300 🡪 600; ACTH inappropriately normal or low (normal <10.1Umol/L). What are the differential diagnoses?

A

Adrenals are still very responsive due to acute nature = hence optimal rise

Eg: Post Pituitary Surgery, Pituitary Apoplexy (Sheehan’s syndrome from PPH)

OR Patient was given a few doses of dexamethasone by family physician few days before admission (dexamethasone would suppress the exogenous glucocorticoid function, explaining low 0 min level. However, as the adrenals are not atrophied yet, the adrenal would mount a robust response to Synacthen administered).

23
Q

When doing short synacthen test, 50 🡪 60 🡪 70; ACTH inappropriately normal or low (normal <10.1Umol/L). What are the differential diagnoses?

A

Adrenals are no longer responsive due to chronic suppression = suboptimal rise

Eg: 6 weeks post Pituitary Surgery; chronic steroid use

24
Q

What is the management of exogenous Cushing?

A

Stop all exogenous steroids (esp TCM, b/c steroid dose is uncontrolled)

Give controlled & small steroid dose @ physiological levels

  • Hydrocortisone 10mg on waking, 5mg at 5pm
  • Mild-moderate illness (eg: runny nose, sore throat) <39 degrees 🡪 2x dose for 2-3 days till mild illness is over
  • Severely unwell >39 degrees / severely unwell, diarrhoea, vomiting 🡪 Please come to hospital for parenteral steroids – b/c you are at HIGH RISK of Addisonian crisis

Continue steroid provision until axis “wakes up”: However, if extremely chronic use of TCM 🡪 Axis may NEVER wake up, requiring life-long steroids

25
Q

What are the 3 tests to confirm Cushing’s if there is no exogenous steroid use?

A

4hr Urinary Free Cortisol (Preferred method)

  • +ve if urine cortisol is 2-3x the ULN
  • How: ask patient to pee into a bottle for the entire day
  • C/I in pt w/ CKD or ESRF and reduced urine o/p

Overnight Low-Dose (1mg) Dexamethasone suppression test

  • How: Take 1mg at 11pm 🡪 check cortisol next morning 8am, looking for suppression of cortisol levels
  • If completely suppressed: normal = suppressed to <50
  • If not completely suppressed: Cushing’s

Late-night Salivary Cortisol: Cortisol is supposed to drop at night, hence if high = absence of diurnal variation

26
Q

What are the investigations to determine the etiology of Cushing’s disease?

A

1) First assess ACTH levels: to assess if ACTH
- Dependent or ACTH independent
- If low = adrenal problem: i.e. ACTH INDEPENDENT
- If high = non-adrenal problem 🡪 may be pituitary or CA i.e. ACTH DEPENDENT

2) If ACTH Dependent
- to assess if CD or Ca
- We can differentiate between the 2 via either of 2 tests below

OPTION 1: Overnight High Dose Dexamethasone Suppression test (8mg)

  • How: 8mg Dexa at 11pm 🡪 check cortisol at 8am
  • If >50% suppression = likely pituitary tumor
  • Confirm w/ MRI scan for tumor 🡪 Trans-sphenoidal resection
  • If <50% suppression = likely ectopic ACTH production
  • Rationale: Pit tumor is believed to be less aggressive than Ectopic, and hence High Dose should be able to suppress!

OPTION 2: Bilateral IPSS (Inferior Petrosal Sinus Sampling): GOLD STANDARD

  • How: To take blood from petrosal sinus VS bloods from peripheral (femoral V) 🡪 compare the ACTH levels to see which is higher!
  • If Petrosal Sinus ACTH higher = Cushing’s Disease
  • If Peripheral ACTH same as Petrosal Sinus = Ectopic ACTH
  • ☹ Invasive test

Other investigations after the above tests

1) MRI pituitary
- ☹ Adenoma is often small (a microadenoma) hence MAY NOT be visible
- ☹ May pick up inceidentalomas esp in Elderly
- But should still be done to confirm the Dx!
2) Adrenal CT/MRI
- Helps to localise disease in Primary Cushing’s
- Tumors are relatively large and always detectable by CT scan.

27
Q

What is the management of cushing’s disease?

A

Trans-sphenoidal removal of the tumour 🡪 FIRST LINE!

  • Overall, pituitary surgery results in remission in 75–80% of cases
  • If fails – can consider 1) Re-Op 2) Medical Tx 3) Radiotherapy

External pituitary Radiotherapy (stereotactic therapy)” slow acting, only effective in 50–60% even after prolonged follow-up and mainly used after failed pituitary surgery

Medical Therapy to reduce CTH

Bilateral adrenalectomy

  • Effective last resort in emergency
  • May lead to Nelson’s Syndrome (See 1st page)
28
Q

What is the medical therapy given to first achieve remission for cushing syndrome?

A

Pituitary level

  • Cabergoline” DA agonist, also has some effect on inhibiting ACTH producing pituitary tumors, and not just on Prolactin
  • Pasireotide: Somatostatin Analogue

Adrenal level synthesis

  • Ketoconazole (Antifungal)
  • Metyrapone
  • Mitotane

Adrenal level Cortisol receptor blocker
- Mifepristone

29
Q

How do you withdraw glucocorticoid therapy safely?

A

For patients with adrenal insufficiency: will require lifelong replacement BUT

Otherwise, patients on chronic steroid therapy can tail down steroid use via:

  • Tail down current steroid dose in a stepwise manner over weeks until minimum replacement dose (Prednisolone 7.5mg OM or Dexamethasone 2mg OM)
  • At minimum replacement dose 🡪 convert to Hydrocortisone 10mg OM and 5mg at 5pm
  • Omit Hydrocort for 24 hours 🡪 perform SST
  • Restart PO hydrocortisone whilst awaiting the results of SST
  • IF 30min or 60min cortisol < 500nmol/L 🡪 keep pt on Hydrocortisone 10mg OM & 5mg at 5pm for another 3 months 🡪 repeat SST
  • IF 30min or 60min cortisol > 500nmol/L 🡪 safe to discontinue completely

Endocrine (18 decks)

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