A 69 yo male with a history of previous pneumonectomy for lung carcinoma, is admitted with confusion. There were no focal neurological signs on clinical examination. Neck stiffness was not present. Contrast CT brain scan is normal
His initial plasma biochemistry is shown:
|
Na+ |
148 mmol/L |
(134-145) |
|
K+ |
3.7mmol/L |
(3.5-5.0) |
|
Cl- |
109mmol/L |
(97-107) |
|
HCO3- |
33mmol/L |
(24-34) |
|
Albumin |
15 G/L |
(35-40) |
|
Urea |
12.8 mmol/L |
(3.1-8.1) |
|
Creatinine |
36 micromol/L |
(60-100) |
|
Ca++ |
2.59 mmol/l |
(2.20-2.55) |
|
Phosphate |
0.86 mmol/L |
(0.78-1.43) |
|
Mg++ |
0.89 mmol/L |
(0.67-1.05) |
a) What is the most likely cause of the confusion in this patient, based on the above information? Justify your response.
List 4 therapies for the cause stated in a)
Hypercalcemia (When corrected for albumin, the true calcium is higher).
Extra marks for recognising the inaccuracy of this correction
List 4 therapies for the cause stated in a)
Calciuresis (saline +/-frusemide)
Bisphosphonates
Calcitonin
Corticosteroids
NSAIDS
Mithramycin
This question resembles Question 18.1 from the first paper of 2011- or rather, the answer to this question. Again, hypercalcemia is brought out.
In this case, however, it is "occult" hypercalcemia, obscured by the normal-looking numbers.
But, if one corrects for the albumin...
Corrected calcium = (0.02 × (normal albumin - patient's albumin)) + serum calcium
or
Ca++ = (0.02 × (40-15) + 2.59
Thus,
Ca++ = 3.09
This formula was first described by Payne et al in 1973.
In brief, these are the physiological aims for management of hypercalcemia, and the means to achieve them:
Payne, R. B., et al. "Interpretation of serum calcium in patients with abnormal serum proteins." British Medical Journal 4.5893 (1973): 643.