Patient with blunt pain in the elft thigh

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Mr. L.K. (55 years, 175 cm, 95 kg) arrived to the doctor’s with cough and mild fever, fatigue and weakness. A direct question about pain revealed long-term blunt pain in the left thigh (“deep inside”). Chest auscultation found bronchitic crackles, heart without murmurs.

Question 1: Which causes of thigh pain are plausible and why? Which causes are, on the other hand, unlikely?

The doctor is very diligent so he collects blood samples for biochemical analysis, blood count and sedimentation.

Results (only abnormal):

sedimentation 50 mm/h

leukocytes 13×10^9/l

blood glucose 6.2 mmol/l

total cholesterol 6.1 mmol/l

triacylglycerols 2.1 mmol/l

total Ca²⁺ 2.0 mmol/l

total ALP 7.8 μkat/l

Question 2:

Based on patient history, physical and laboratory assessment, which other tests would you suggest?

What could abnormal values of Ca2+ and total ALP mean?

What could explain abnormal blood glucose and cholesterol in this patient?

Due to the protracted thigh pain the doctor ordered an X-ray, which showed an altered structure of the left femur, but without any gross pathology. The patient was then sent for bone scintigraphy.

Question 3:

Describe the principle of this test. What compounds are used to detect abnormalities and why? What is the difference between scintigraphy and positron emission tomography (PET)?

Based on these examinations and differential diagnosis the patient started taking the medicament etidronate.

Question 5:

What is the structure of etidronate, what other biologically relevant molecule does it resemble and what is its mechanism of action?

After a few weeks of this treatment Mr. L.K. came back to see the doctor and complained once again about fatigue. Detailed tests revealed increased blood concentration of parathormone and hypocalcemia.

Question 6:

How could these laboratory findings be related to each other and to Mr. L.K.’s condition?

What is the most likely diagnosis of Mr. L.K.?