ملخص لملزمة الكيمياء مال adrenal
Investigations of Suspected Adrenocortical Hyperfunction

Screening Tests for Cushing’s Syndrome
1. Low-dose Dexamethasone Suppression Test (Overnight Test):
• Purpose: Best initial outpatient screening test for adrenocortical hyperfunction.
• Procedure:
• The patient takes 1 mg dexamethasone at 11–12 PM.
• Serum cortisol is measured the next morning between 8–9 AM.
• Interpretation:
• A cortisol concentration <50 nmol/L excludes Cushing’s syndrome.
• Accuracy:
• False-positive rate: ~12%.
• False-negative rate: <2%.
• Notes:
• A 48-hour suppression test is more accurate but less convenient:
• Dexamethasone 0.5 mg every 6 hours starting at 9 AM for 2 days.
• Serum cortisol measured at 48 hours.
• True-positive rate: >97%.
• False-negative rate: <1%.
• Important:
• Drugs like phenytoin, phenobarbitone, fluoxetine (affect hepatic enzymes) can alter results.
• False positives: Can occur in women on oral contraceptives or with poorly controlled diabetes.

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2. Urinary Free Cortisol (UFC):
• Basis:
• Measures biologically active cortisol excreted in 24-hour urine.
• Interpretation:
• Cushing’s is generally excluded if UFC is <250 nmol/24 h.
• Disadvantages:
• Incomplete urine collection can cause false-negative results.
• Accuracy:
• False-negative rate: 8–15% even with correct collection.

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3. Late Night Salivary Cortisol:
• Basis:
• Measures free cortisol reflecting the biologically active fraction.
• Allows home collection between 11 PM and midnight.
• Accuracy:
• Reported sensitivity and specificity: 92–100%.
• False positives:
• Can occur due to contamination from steroid lotions, oral gels.
• Higher values seen in elderly, smokers, hypertensives, diabetics.
• Important:
• Should be avoided in shift workers or people with variable bedtimes.
• Additional use:
• Very useful in detecting mild cases of Cushing’s.
• Useful for diagnosis and monitoring treatment.

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Interpretation of Screening Tests
• Purpose: Distinguish simple obesity from Cushing’s-related obesity.
• False positives:
• May occur in depression, severe illness, alcoholism (pseudo-Cushing syndrome).

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Confirmatory Tests
1. Loss of Diurnal Rhythm:
• Normal physiology:
• Plasma cortisol highest in early morning, lowest at midnight.
• In Cushing’s:
• Midnight cortisol is elevated even if 8 AM cortisol is normal.
• Procedure:
• Hospitalize patients for 48 hours.
• Use stress-free venipuncture (e.g., indwelling catheter).
• Collect 24-hour urine samples for UFC.
• Pseudo-Cushing’s:
• May also show disturbed rhythm.
• Differentiated using ACTH response to CRH.
• Special clue in alcoholism:
• Raised MCV (Mean Cell Volume).
• Abnormal liver function tests.
• Abstinence leads to HPA axis normalization.

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Determining the Cause of Cushing’s Syndrome
1. Plasma ACTH Measurement:
• Notes:
• ACTH is unstable.
• Collect into EDTA tubes, separate plasma and freeze within 30 minutes.
• Timing:
• Measure at 8 AM and 10 PM.
• Interpretation:
• Undetectable ACTH → Suggests functional adrenal tumor → Confirm by CT/MRI.
• Detectable or high ACTH → Suggests pituitary-dependent Cushing’s or ectopic ACTH.
• Special note:
• Very high ACTH usually points toward ectopic source.

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2. High-dose Dexamethasone Suppression Test:
• Procedure:
• 2 mg dexamethasone every 6 hours for 48 hours.
• Compare pre- and post-test cortisol levels.
• Interpretation:
• Suppression = cortisol falls to <50% of baseline.
• Alternative:
• 8 mg dexamethasone overnight can substitute with similar accuracy.
• Diagnostic utility:
• About 90% of pituitary-dependent Cushing’s patients show suppression.
• Only about 10% of ectopic ACTH patients suppress cortisol.

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3. CRH Stimulation Test:
• Procedure:
• Inject 100 µg of CRH.
• Measure ACTH and cortisol at baseline(0), 15, 30, 45, 60, 90, and 120 minutes.
• Interpretation:
• Normal individuals (and depressed patients):
• ACTH peak <120 ng/L.
• Cortisol peak ~700 nmol/L.
• Ectopic ACTH or adrenal tumor:
• Little or no response to CRH.

• Pituitary Cushing’s:
• Exaggerated ACTH and cortisol response.
• Diagnostic performance:
• CRH test specificity ≈ 95%.
• When combined with high-dose dexamethasone suppression → nearly 100% specificity and sensitivity for diagnosing pituitary Cushing’s disease.

هذا يشرح الفحوصات بشكل عام وهسه راح ادزلكم شرح للخطوات اشلون نستخدم هاي الفحوصات....والشرح يمشي ويه ال figure الثاني flow chart

(Plan of Investigations for Suspected Cushing’s Syndrome)

1– First Step: Screening Tests
A– Perform one or more of the following initial screening tests:
• Low-dose dexamethasone suppression test
• Urinary free cortisol (UFC)
• Late-night salivary cortisol

2– Second Step: Interpretation of Screening Results
A– If screening tests are normal -
• Cushing’s syndrome is excluded (no further testing needed)
B– If screening tests are abnormal -
• Cushing’s syndrome is likely, so move to confirmatory tests

3– Third Step: Confirmatory Test
A– Check for loss of diurnal cortisol rhythm -
• Measure midnight cortisol (in blood or saliva)
• OR perform multiple UFC measurements over 24-hour urine collections

4– Fourth Step: Measure Plasma ACTH
A– If ACTH is undetectable or very low -
• This suggests an adrenal cause (adrenal adenoma or carcinoma)
• Next step → Perform CT or MRI of adrenal glands
B– If ACTH is normal or elevated -
• This suggests an ACTH-dependent cause (either pituitary or ectopic ACTH)

5– Fifth Step: Differentiating Pituitary vs. Ectopic ACTH Source
A– Perform a High-dose dexamethasone suppression test
B– Perform a CRH stimulation test

6– Sixth Step: Interpretation to find the source
A– If cortisol suppresses after high-dose dexamethasone OR shows exaggerated ACTH/cortisol response after CRH -
• Likely diagnosis = Cushing’s disease (pituitary cause)
• Next step → Perform MRI of the pituitary gland to locate the tumor
B– If cortisol does not suppress after high-dose dexamethasone AND no response to CRH -
• Likely diagnosis = Ectopic ACTH production
• Next step → Search for ectopic source (e.g., small cell lung cancer, carcinoid tumors)→ Perform CT/X-ray of the chest to confirm the diagnosis, and don't forget the tumour markers

ترتيب النصوص اعلاه ذكاء اصطناعي اما المعلومات من الملزمة والمصدر وتغطي كل المطلوب منكم فالمعلومات غاية بالدقة 💯

ضيفولها mild acidosis و diarrhea و abdominal pain و nausea و vomiting وبهاي الطريقة اتكون شاملة ان شاء الله

وهذني هم يفيدنكم لان بعض الاشياء الي فوگ تؤدي الى اعراض معينة مكتوبة اهنا....

هذني مميزات لل adrenal crisis الي هي نفسها acute adrenal insufficiency

and don't forget High potassium is dangerous because it can cause cardiac arrhythmias, especially if K⁺ >6.0 mmol/L.
That’s why in adrenal crisis, we should not only give hydrocortisone and fluids — we should also monitor EKG for signs of hyperkalemia like:
1-Peaked T waves
2-Widened QRS complex
3-Risk of sudden cardiac arrest.

وهاي ال causes لل adrenal insufficiency من الاكثر شيوعاً ونازل بس ملاحظة انه ال acute adrenal insufficiency واحد من اسبابه الشائعة انه تقطع علاج مريض ياخذ corticosteroids لمدة اسبوعين او اكثر بدون tapering

Why does diarrhea occur in the absence of aldosterone?

In the absence of aldosterone, the intestines — especially the colon — are unable to effectively absorb sodium (Na⁺). less sodium absorption means less water is reabsorbed from the intestinal lumen back into the body.


No aldosterone → no sodium absorptionبالامعاء → بالامعاء no water reabsorption → diarrhea.

#معلومة_عالسريع

فرط نشاط الغده الدرقيه يزيد الضغط الانقباضي
hyperthyroidism > systolic HTN
خمول الغده الدرقيه يزيد الضغط الانبساطي
hypothyrodism > diastolic HTN

فيما يخص الصور الي تجي بالامتحان الصور بملازم الباثو اثنينهن بملازم دكتور مهند داخلات بالاضافة الى ملزمة العملي


اما ملزمة دكتورة هبة ماداخله كصور بالعملي... بس نظري.


بالنسبة للتشريح سبق وان قلنا انه الصور بملازم النظري داخلة وملازم العملي كذلك داخلة ماعدى صور ال electron microscope ما داخله واكثر شيء ركزوا على صور الانسجة

عندكم صور باول اسبوع مال radiology ذني جداً مهمات ركزوا عليهن


بالنسبة للتأشير فهي اغلب الصور اذا مو كلهن مؤشرات وواضحات...

الله يسهل عليكم 🙏✨

إحدى الشخصيات المهمة جداً وذات النفوذ الذي يمنع حتى الطلبة من الدراسة في يوم قبل الامتحان

1-Cushing +High ACTH = ACTH-dependent
(pituitary tumour أو ectopic)
حتى نفرق بينهن :

Give CRH INJECTION :

-if ACTH INCREASE :pituitary adenoma
-if ACTH not highly effected : Ectopic ACTH

-او ننطي ديكساميثازون جرع عالية اذا تثبط ال ACTH والكورتيزول شوية فهاي pituitary tumour
او ندور على pituitary adenoma ب MRI +CT

2-Low ACTH + Cushing = adrenal tumor
-FEEDBACK