A case of persistent hypocalcemia

HOSP # MRN63985901 WARD Medical Ward
CONSULTANT Dr. Heleen Vreede   DOB/AGE 51 year Female

Abnormal Result

Total calcium of 1.47 mmol/L (2.15 – 2.50)

Presenting Complaint

The patient has been having persistent hypocalcemia despite supplementation with calcium.

History

Figure 1 – Illustration of the patient’s CMP over time:
Calcium: blue; Magnesium: orange; Phosphate: grey
Reference ranges are the horizontal lines without dotted markers

Examination

Not available.

The typical findings in a patient with true hypocalcemia (low ionised calcium) are

Trouseau’s sign

Chvostek’s sign

Laboratory Investigations

Arguably, the first important consideration in patients with low calcium is the albumin. The patient had a mean albumin of 12 g/L, significantly lower than normal (40-50g/L). Arguably, the calcium can be corrected with the well known Payne’s formula to then be 1.47 + (0.02 x (40-12) = 2.03 mmol/L:

Albumin-adjusted calcium (mmol/L) = total calcium (mmol/L) + 0.02 [40 – albumin (g/L)])

Payne RB, Little AJ, Williams RB, Milner JP. Interpretation of serum calcium in patient with abnormal serum proteins. Br Med J. 1973;4:643-646. DOI: 10.1136/bmj.4.5893.643. (View)

Measurement of serum intact parathyroid hormone (PTH) should be performed in all patients with hypocalcemia; it is the most valuable laboratory test for determining the etiology of hypocalcemia:

  2019/11/15 2019/06/28 2018/08/03
PTH (pmol/L)  21,8 H  15,5 H  25,8 H
Reference interval: (1.6-6.9 pmol/L)

Vitamin D

09/09/2020 15/11/2019 03/08/2018
Total Vitamin D (25-OH VitD) 20.5 nmol/L 45.4 nmol/L 23.2 nmol/L
Guidelines for assessment of Vitamin D status:
<30 nmol/L <12 ng/mL Deficient
30-50 nmol/L 12-20 ng/mL Insufficient
>50 nmol/L >20 ng/mL Sufficient
125-150 nmol/L 50-60 ng/mL Safe upper limit
Reference: Revised South African Clinical Guideline for the diagnosis and management of osteoporosis (NOFSA 2017), endorsing the institute of Medicine Dietary Reference intakes for calcium and vitamin D (2010). Note regarding conversion of units:
Divide result in nmol/L by 2.496 to convert to ng/mL
Multiply result in ng/mL by 2.496 to convert to nmol/L

Other Investigations

Anti-Tissue Transglutaminase antibodies: Negative: repeated 3 months apart, with sufficient IgA levels in the serum): 0.9 & 0.8 U/mL (EliA c/o: 6.9)

Anti-Gliadin antibodies: Equivocal: 7.8 & 9.6 U/mL (EliA c/o: 6.9)

Anti-endomysial antibodies: Negative

HLA-DQ2: Positive

HLA-DQ8: Negative

Final Diagnosis

Hypocalcemia likely due to malabsorbtion (telangiectasia stated by the clinicians).

Take Home Message

According to International guidelines the following association is expected for patients with Coeliac Disease:
Positive for HLA-DQ2 (HLA-DQA1*05, DQB1*02)
Positive for HLA-DQ8 (HLA-DQA1*03, DQB1*03:02)

Considering the fact that the albumin was high with an increased PTH, the calcium very likely was physiologically also low (bioactive Ca). The Payne’s formula also failed to correct the calcium to the normal reference range.

Cumulative History:Download