Case study 018

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You have completed Case study 018. Your score is %%PERCENTAGE%%. %%RATING%%

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Question 1

Matt is a37-year-old lab technician presented to his family physician with generalised aching pains, anorexia, and constipation for about 3 months duration. He also had polydipsia, and polyuria. Matt had a history of recurrent renal stones over the past 2 years. He had a 4-year history of hypertension which is well controlled using beta blockers.

On examination:

Height: 170 cm, Weight: 78 Kg, BMI: 27.0
BP: 140/95 mmHg, Heart rate: 68 /m, Respiratory rate: 16 /m, Temperature: 37.1⁰C, O₂SAT: 98%

What is the most common type of renal stones?

A	Calcium phosphate
B	Calcium oxalate
C	Uric acid
D	Cystine
E	Struvite

Question 1 Explanation:

All of the above can be components of renal stones. The most common composition of kidney stones is calcium oxalate.

Question 2

All the following contribute to recurrent renal stones, EXCEPT:

A	Recurrent urinary tract infection
B	Hypercalciuria
C	Hypercitraturia
D	Low urine volume
E	Oxalate-rich food

Question 2 Explanation:

Citrate in the urine helps prevent the formation of kidney stones, because it forms a complex with calcium and inhibits crystal formation. Therefore, it is hypocitraturia which contribute to renal stone formation. All other factors can be the cause of recurrent renal stones.

Question 3

Matt’s laboratory investigation showed:

Urinalysis:
- Color: amber yellow, pH: 6.9, Specific gravity: 1008, Osmolarity : 232 mOsmol/kg; Glucose, Ketones, Albumin, Bilirubin: negative, WBCs and RBCs: 1 and 2/HPF, Epithelial cells, Casts, Yeast: negative, Bact: 1-2, Uric acid crystals: ++,
- Urinary calcium: 11.8 mmol/24 hours
Blood analysis:
- CBC:
  - Hemoglobin: 145.5 g/L, Hematocrit: 0.43
  - RBCs: 4.1 x 10¹²/L, MCV: 86 fL, MCH: 30 pg, RDW: 13.1%, Reticulocytes: 9.0%, ESR: 7 mm/hour
  - WBC: 7.5 x 10⁹/L, (Neutrophils: 4.1 x 10⁹/L, Lymphocytes: 2.7 x 10⁹/L, Basophils: 0.05 x 10⁹/L, Eosinophils: 0.31 x 10⁹/L, Monocytes: 0.7 x 10⁹/L)
  - Platelet counts: 218 x 10⁹/L
- Na: 140 mmol/L, K: 4.0 mmol/L, Cl: 100 mmol/L, Ca (total): 3.1 mmol/L, Ca (ionized): 1.9 mmol/L, P: 0.6 mmol/L, Mg: 84 mmol/L
- Glucose: 5.7 mmol/L, Creatinine: 118.8 µmol/L, Uric acid: 312 mmol/L
- Triglycerides: 2.5 mmol/L, Cholesterol: 5.9 mmol/L, HDL: 0.9 mmol/L, LDL: 2.9 mmol/L
- Bilirubin: 12 mmol/L, Albumin: 43 g / L, ALP: 122 U/L

What does the high calcium level indicate in Matt’s case?

A	Parathyroid disease
B	Thyroid gland disorder
C	High dietary calcium intake
D	Dehydration

Question 3 Explanation:

In case of recurrent kidney stones and high serum and urinary level of calcium the parathyroid gland should always be further investigated.

Question 4

Which of the following hormones correctly matches with its effect on calcium metabolism:

A	Calcitonin – increases the calcium absorption from the intestine to increase serum calcium level
B	Parathyroid hormone – inhibits osteoclast activity in bones to reduce serum calcium level
C	Parathyroid hormone – stimulates active Vitamin D production in the kidneys to elevate serum calcium level
D	Calcitonin – stimulates osteoblast activity in bones to reduce serum calcium level
E	Calcitriol (active vitamin D) – decreases serum calcium level through inhibition of calcium absorption from the intestine

Question 4 Explanation:

Parathyroid glands, which are located on the posterior surface of the thyroid gland, play an important role in calcium homeostasis. They produce parathyroid hormone (parathormone) which increases serum calcium level through stimulation of calcitriol (active vitamin D), calcium release from bones and calcium reabsorption in kidneys. Calcitriol increases serum calcium level through stimulation of calcium absorption from the intestine.

Question 5

Let’s have a look at Matt’s serum hormone levels:

- TSH: 1.2 µU/mL, Total T₄: 83.2 nmol/L, Free T₄: 13 pmol/L, Total T₃: 2.4 nmol/L, Free T₃: 4.8 pmol/L
- 25-(OH)D₃: 19 nmol/L
- Aldosterone (recumbent): 0.16 nmol/L,
- Parathyroid hormone (PTH): 13.3 pmol/L

What is Matt’s diagnosis? Explain your answer.

A	Hyperthyroidism
B	Hyperparathyroidism
C	Hyperaldosteronism
D	Vitamin D (25-(OH)3) deficiency

Question 5 Explanation:

Hyperparathyroidism is a condition when the parathyroid glands overproduce parathyroid hormone. This condition results in elevated serum calcium level (hypercalcemia), calcium in the urine (hypercalciuria), higher risk of osteoporosis and renal stones.

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