Case study 020

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Question 1

Anna is a 40-year-old female, who is presented with headache, muscle cramps and weakness. She also complained of increased thirst and frequent urination which wakes her up from sleep at night. She also reported that she has uncontrolled high blood pressure despite taking her medications as prescribed.

On examination:

Height: 167 cm, Weight: 66 kg, BMI: 23.7
BP: 176/105 mmHg, Heart rate: 96/min, Respiratory rate: 20/min, Temperature: 37.0⁰C, O₂SAT: 98%

According to Anna’s clinical condition, which of the following initial laboratory tests would you begin with? (select top three tests):

A	Blood glucose level
B	Serum electrolytes
C	Hemoglobin level
D	Urine osmolarity
E	Plasma TSH
F	Serum calcium

Question 1 Explanation:

Serum sodium and potassium levels are important initial routine tests particularly in a patient whose blood pressure is uncontrolled and is always thirsty. The same applies to urine osmolarity. Blood glucose level rules in/out diabetes mellitus in a patient who has polyuria and polydipsia.

Question 2

Here are Anna's laboratory test results:

Blood analysis:
- CBC:
  - RBCs: 4.2 x 10¹²/L, Hemoglobin: 133.5 g/L, Hematocrit: 0.40
  - MCV: 93 fL, MCH: 31 pg, RDW: 11.8%, Reticulocytes: 1%, ESR: 9 mm/hour
  - WBC: 6.8 x 10⁹/l, (Neutrophils: 3.0 x 10⁹/L, Lymphocytes: 2.8 x 10⁹/L, Basophils: 0.02 x 10⁹/L, Eosinophils: 0.22 x 10⁹/L, Monocytes: 0.9 x 10⁹/L)
  - Platelet counts: 217 x 10⁹/L
- Na: 144 mmol/L, K: 2.9 mmol, Cl: 102 mmol/L , Total Ca: 2.64 mmol/L, Ionized Ca: 1.44 mmol/L, Glucose: 5.2 mmol/L, Creatinine: 69.3 u mol/ L, Uric Acid: 243 mmol/L
- Triglycerides: 2.0 mmol/L, Cholesterol: 4.7 mmol/L, HDL: 1.2mmol/L, LDL: 2.4 mmol/L
- Bilirubin: 9 mmol/L, Albumin: 47 g / L
- Serum cortisol (8 am): 207 nmol/L
Urine analysis:
- Color: yellow, pH: 5.0, Specific gravity: 1012, Osmolarity : 306 mOsm/kg; Glucose, Ketones, Albumin, Nitrate, Bilirubin: negative, WBCs and RBCs: 0/HPF, Squamous epithelial cells, Casts, Bacteria, Yeast: negative, Oxalate crystals: +

Which of the following urine or blood tests would be important to interpret and react to? (select only one)

A	Urine osmolarity
B	Serum Na
C	Total serum calcium level
D	Serum K level
E	Serum cholesterol level
F	Blood glucose level
G	Total white cell count

Question 2 Explanation:

Serum potassium is primarily maintained through the RAAS (Renin-Angotensin-Aldosterone System). Abnormal level of potassium is dangerous and can be life-threatening.

Question 3

Further blood tests were requested and the results are the followings:

Blood tests:
- Aldosterone (recumbent): 4.56 nmol/L,
- Renin activity: 0.25 ug/L/hour,
- Plasma aldosterone concentration/Plasma renin activity: 18.24
After Captopril Suppression Test:
- Aldosterone (recumbent): 4.55 nmol/L
- Renin activity: 0.23 ug/L/hour
Urine analysis after 24 hours:
- K excretion: 179 mmol/24
- Aldosterone: 112 nmol/24 hours
- Cortisol, free: 143 nmol/24 hours
- Catecholamines, total: 254 nmol/m²/24 hours

Which of the following hormones is most likely over-secreted in Anna’s condition?

A	Thyroxine
B	Insulin
C	Catecholamines
D	Aldosterone
E	Cortisol

Question 3 Explanation:

Explanation: Anna’s laboratory results show hypernatremia and hypokalemia. In this case hypersecretion of aldosterone (Conn’s syndrome) should be suspected and further investigated. Conn's syndrome is associated with low renin activity.

Question 4

What is the effect of aldosterone in the body?

A	It stimulates the reabsorption of sodium and water and the secretion of potassium ions.
B	It inhibits the reabsorption of sodium and water and the secretion of potassium ions.
C	It stimulates the secretion of sodium and water and the reabsorption of calcium and potassium ions.
D	It inhibits the secretion of sodium, water, and potassium ions in urine.

Question 4 Explanation:

Aldosterone stimulates the reabsorption of sodium and water and the secretion of potassium ions in the renal tubules.

Question 5

Beside measuring serum aldosterone concentration, what specific laboratory test is available to further investigate hyperaldosteronism?

A	ACTH stimulation
B	Water deprivation test
C	Captopril suppression test
D	Dexamethasone suppression test
E	Captopril challenge test

Question 5 Explanation:

Please, refer to the explanation of these tests in the "Methodology of laboratory tests" section on our website.

Question 6

How do you explain if high renin activity is associated with hyperaldosteronism?

A	It means that the patient has high blood pressure.
B	It means that the patient has acute renal failure.
C	It means that hyperaldosteronism is secondary to increased RAAS activity.

Question 6 Explanation:

In primary hyperaldosteronism (Conn’s syndrome), typically the patient has hypernatremia, hypokalemia, and high blood pressure, which would result in low renin activity. In secondary hyperaldosteronism however, the renin activity is high which proves the over stimulation of the renin-angiotensin aldosterone system (RAAS). One of the most common causes is renal hypoperfusion.

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