Case study 008

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Question 1

Amy is a 19-year-old, presented with a 3-month history of fatigue, drowsiness, loss of appetite, weight loss, and craving for salty foods. A couple of weeks ago, she fainted several times while standing up. She has also been complaining of headaches. Amy had no significant past medical history.

On examination:

Weight: 50.8 Kg, Height: 159 cm, BMI: 20.1
BP: 95/63 mmHg (sitting), 82/45 mmHg (standing), Heart rate: 102/min, Respiratory rate: 22/min, Temperature: 36.9⁰C, O₂SAT: 98%
Hyperpigmented skin was noticed on her hands, nipples, and buccal mucosa

According to Amy’s symptoms and signs, what electrolyte disturbances could be expected?

A	Hypokalemia
B	Low urine sodium
C	Hyponatremia
D	Hypocalcemia
E	Normal plasma sodium
F	Normal plasma potassium
G	Hypernatremia

Question 1 Explanation:

Common symptoms of hyponatremia include weakness, fatigue, low blood pressure, headache, and muscle cramps. Amy is also craving for salty food, lost some weight and has hyperpigmentation on specific areas of her skin.

Question 2

Here are Amy’s laboratory test results:

Blood analysis:
- CBC:
  - Hemoglobin: 123 g/L, Hematocrit: 0.37
  - RBCs: 3.9 x 10¹²/L, MCV: 90 fL, MCH: 28 pg, RDW: 13.7%, Reticulocytes: 1.2%, ESR: 8 mm/hour,
  - WBC: 7.0 X 10⁹/L, (Neutrophils: 4.7 x 10⁹/L, Lymphocytes: 6.1 x 10⁹/L, Basophils: 0.04 x 10⁹/L, Eosinophils: 1.4 x 10⁹/L, Monocytes: 0.43 x 10⁹/L)
  - Platelet counts: 217 x 10⁹/L
- Na: 120 mmol/L, K: 5.5 mmol/L, Ca: 2.9 mmol/L (total), 1.8 mmol/L (ionized), Glucose: 3.5 mmol/L, Creatinine: 64.2 umol/L, BUN: 8.2 mmol/L, Uric acid: 234 mmol/L, Plasma osmolarity: 273 mmol/kg
- Triglycerides: 1.6 mmol/L, Cholesterol: 3.9 mmol/L, HDL: 0.9 mmol/L, LDL: 2.4 mmol/L
- Bilirubin: 7 mmol/L, albumin: 42.8 g/L
- TSH: 2.8 uU/mL, Total T₄: 117 nmol /L, Free T₄: 12 pmol/L, Total T₃: 1.9 nmol/L, Free T₃: 4.6 pmol/L,
- C- Peptide: 0.26 nmol/L
- Renin activity: 26 ug/L/hour
- ACTH (8 am): 26 pmol/L, cortisol (8 am): 60 nmol/L, 30 min after ACTH injection: 70 nmol/L
- 21-hydroxylase antibody: positive
Urine analysis:
- Color: yellow, Specific gravity: 1025, Osmolarity: 895 mmol/Kg, pH: 6.8, Glucose, Bilirubin, Ketones, Albumin, Nitrate: negative, RBCs and WBCs: 0-4/HPF, Squamous epithelial cells: 1-2/HPF, Casts, Bacteria, Crystals, Yeast: negative.

Based on these laboratory test results, which of the following hormone secretion is/are insufficient? (select all that apply)

A	Thyroxine
B	Aldosterone
C	Anti-diuretic hormone
D	Cortisol
E	Calcitonin
F	Glucagon

Question 2 Explanation:

Amy' s clinical signs and symptoms, such as fatigue, orthostatic hypotension, weight loss, hyponatremia, hyperkalemia indicative for the disorder of the adrenal gland, which produces aldosterone and cortisol.

Question 3

What is the significance of measuring the renin activity?

A	To determine if her low blood pressure is caused by the excess of the renin hormone.
B	Renin activity should be elevated in primary adrenal insufficiency.
C	High renin activity would cause overproduction of aldosterone and cortisol.
D	Renin causes reabsorption of potassium, so if renin activity is low that would result in hyperkalemia.

Question 3 Explanation:

The aldosterone secretion is primarily regulated by the renin angiotensin aldosterone system (RAAS). Hypovolemia and hyperkalemia stimulate renin secretion which stimulates aldosterone production. In adrenal insufficiency (Addison’s disease), we can expect higher renin activity because the sodium loss -that is caused by the lack of aldosterone- results in hypovolemia, which stimulates the renin secretion in the kidney. Higher renin activity in Amy’s case is an expected finding and confirms her diagnosis.

Question 4

What is the diagnosis of Amy’s condition?

A	Cushing's syndrome
B	Grave's disease
C	Addison's disease
D	Sheehan's syndrome
E	Acromegaly

Question 4 Explanation:

Amy's diagnosis is Addison's disease, which is primary hypofunction of the adrenal gland. Cushing's syndrome is the hyperfunction of the adrenal gland. Grave's disease is an autoimmune disorder of the thyroid gland. Sheehan's syndrome is a rare form of pan-hypopituitarism caused by pituitary hemorrhage and acromegaly results from the overproduction of growth hormone.

Question 5

Which of the following tests is useful if mild form of Addison’s disease is suspected?

A	ACTH stimulation test.
B	21-hydroxylase antibody testing.
C	Measuring the TSH.
D	Measuring the baseline glucocorticoid hormone levels.

Question 5 Explanation:

In Addison’s disease, the plasma ACTH level is high and administration of synthetic ACTH fails to stimulate the adrenal cortex and adrenal hormone levels remain low.

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