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Endgames Case Review

Hypercalcaemia with undetectable parathormone levels

BMJ 2018; 363 doi: https://doi.org/10.1136/bmj.k4074 (Published 08 November 2018) Cite this as: BMJ 2018;363:k4074
  1. Ilaria Muller, clinical research fellow1 2,
  2. Lakdasa D Premawardhana, consultant physician2 3
  1. 1Thyroid Research Group, Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK
  2. 2Centre for Endocrine and Diabetes Sciences, University Hospital of Wales, Cardiff, UK
  3. 3Section of Endocrinology, Department of Medicine, Ysbyty Ystrad Fawr, Caerphilly, UK
  1. Correspondence to I Muller mulleri4{at}cardiff.ac.uk

A 54 year old woman had unintentional weight loss of 12-19 kg with nausea, abdominal discomfort, and constipation over 2-3 months. She presented acutely with profuse vomiting for three days. She was taking venlafaxine 150 mg/day for bipolar disorder, she smoked (40 pack years), consumed little alcohol, and had no family history of disease. On examination, she was dehydrated, her blood pressure was 106/74 mm Hg, pulse 122 beats/min and regular, and her temperature was 37.2°C. She had a smooth symmetrical goitre with no retrosternal extension or lymphadenopathy, and mild abdominal tenderness. Systems examination was normal. She underwent blood tests, the results of which were normal for renal function, alkaline phosphatase, total protein, globulin, and protein electrophoresis. Abnormal blood test results are shown in table 1.

View this table:
Table 1

Abnormal blood test results

Chest radiography and computed tomography scans of the abdomen and pelvis were normal.

Questions

  • 1. What are the possible causes of this patient’s hypercalcaemia?

  • 2. What is the most likely diagnosis?

  • 3. How would you treat this patient?

1. What are the possible causes of this patient’s hypercalcaemia?

This patient has non-PTH mediated hypercalcaemia (low PTH and high adjusted calcium levels).

In PTH mediated hypercalcaemia, PTH levels are inappropriately raised, ie, detectable, and within or above the reference range. In non-PTH mediated hypercalcaemia, PTH is below the reference range or undetectable. The causes of both are summarised in table 2.

View this table:
Table 2

Causes of hypercalcaemia

Primary malignancies (eg, lung, breast, kidney, skin) cause hypercalcaemia by producing PTH related peptide (PTHrP), and by causing bone destruction. PTHrP produces similar effects to PTH, ie, increases gut and renal tubular calcium absorption, and activates osteoclast bone resorption—all causing an increase in serum …

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