Here are the initial labs:
A kidney ultrasound shows mild bilateral increased echogenicity without hydronephrosis, stones, or cysts. A urinalysis is stable from her most recent clinic visit and urine electrolytes are sent:
Choose the highest yield tests below (more than one choice may be correct)!
Intact parathyroid hormone (iPTH)
Good eye – this patient has hypercalcemia. The iPTH level < 5 pg/mL.
Vitamin D-25 OH & Vitamin-D 1,25 OH
Great! The vitamin D-25OH level is 25 ng/mL (normal 20 – 40 ng/mL). The vitamin-D 1,25 OH (calcitriol) level is 30 pg/mL (normal 25 – 65 pg/mL).
Serum free light chains & serum immunofixation (IFE)
Very good idea for this patient with hypercalcemia. There is no monoclonal protein detected and free light chains are within normal limits, with a normal kappa:lambda ratio.
Parathyroid Hormone-related Peptide (PTHrP)
In this patient with hypercalcemia, this is a reasonable test to send, particularly with the iPTH results! The test has been sent and is pending…
Kidney biopsy
While this patient does have any acute kidney injury (AKI), there are less invasive higher yield tests to go after first here. Try again!
Positron emission tomography (PET) Scan
While this may be a helpful test in search of underlying malignancy, other tests may provide helpful information. Try again!
What is at the top of your differential diagnosis (choose 3)?
Sarcoidosis
Milk alkali syndrome
Primary hyperparathyroidism
Secondary hyperparathyroidism
Multiple myeloma
Humoral hypercalcemia of malignancy
Lymphoma
Tuberculosis
Small cell lung cancer
Renal cell carcinoma
Parathyroid Hormone-related Peptide (PTHrP) results as <2.5 pmol/L. The patient receives 1 liter of intravenous isotonic fluid and her calcium is improving. Several medications are held.
Ah! Your patient’s partner has arrived with a medication list. It includes losartan, chlorthalidone, simvastatin, cholecalciferol, calcium carbonate, acetaminophen and antacids.
Which of the following medications are contributing to this patient’s hypercalcemia (more than one is correct)?
Calcium carbonate
Yes! Both the supplemental calcium and alkali via carbonate are contributing to this patient’s hypercalcemia and clinical picture.
Antacids
Many over-the-counter antacids are in fact calcium carbonate, adding to this patient’s oral calcium and alkali intake.
Chlorthalidone
Thiazide diuretics will increase the reabsorption of calcium, augmenting this patient’s hypercalcemia.
Losartan
While this medication may contribute to AKI in the setting of volume depletion and kidney vascular vasoconstriction, it should not contribute to hypercalcemia. Try again!
Acetaminophen
This medication should not contribute to hypercalcemia. Try again!
Simvastatin
This medication should not contribute to hypercalcemia. Try again!
Cholecalciferol (Vitamin D3)
Cholecalciferol is the vitamin D produced when skin is exposed to sunlight, and requires hydroxylation by both the liver and then kidney to form calcitriol. Vitamin D will increase gut absorption of both calcium and phosphate. Supplemental Vitamin D could explain why this patient’s 25-OH and 1,25OH Vitamin D levels are perhaps inappropriately normal.
What is the cause of this patient’s hypercalcemia?
Sarcoidosis
Milk alkali syndrome
Primary hyperparathyroidism
Secondary hyperparathyroidism
Multiple myeloma
Humoral hypercalcemia of malignancy
Lymphoma
Tuberculosis
Renal cell carcinoma
[/answer]Small cell lung cancer [/answer]Click here to confirm your diagnosis!
Case 49 Index
Case 49 Introduction
Case 49 Physical Exam
NephSIM