Calcinosis in chronic renal disease

Clinical History

A middle-aged female patient presented to the emergency department after a fall with right hip and shoulder pain. The patient’s past medical history is significant for uncontrolled hypertension, type 2 diabetes, and end stage renal disease (ESRD) on peritoneal dialysis.

Imaging Findings

Chest radiographs showed extensive soft tissue ossification around the left and right acromioclavicular joints with osteolysis of the distal clavicle and erosion of the left glenoid and lateral left scapula. (Fig. 1) These findings were consistent with imaging on upper extremity CT scan (Fig. 2)
X-ray of left femur showed no acute fracture but there was vascular calcification of the left thigh, likely of the femoral artery. This calcification is greater than expected for a patient of this age (Fig. 3).
The combination of ESRD, serum chemistry abnormalities, and calcinosis warranted SPECT imaging with Technetium 99 sestamibi due the possibility of parathyroid involvement. SPECT images showed activity in both lobes of the mildly enlarged thyroid, left lobe larger than the right. There was a relative increase in the lower pole of the right lobe medially and irregularity of activity in the lower pole of the left lobe (Fig. 4).

Discussion

Severe chronic kidney disease (CKD) causes an array of serum chemistry abnormalities due reduced glomerular function. Impaired filtration often leads to hyperkalaemia, uraemia, and hyperphosphataemia. CKD also involves reduced production of erythropoietin and the active metabolite of Vitamin D (1, 25-dihydroxycalciferol) resulting in anaemia and reduced calcium absorption in the GI tract. Reduced calcium levels promotes an increase in parathyroid PTH production in efforts to replenish serum calcium levels from bone stores, which ultimately leads to secondary hyperparathyroidism.[1] Increasing calcium and phosphorus product leads to accumulation of calcium hydroxyapatite and amorphous calcium-phosphate in soft tissues, joints, organs, and arteries.[1]

Recent labs showed elevated creatinine (10.54 mg/dL), elevated BUN (36 mg/dL), low calcium (4.5mg/dL), elevated phosphorus (7.5 mg/dL), and an extremely elevated parathyroid hormone (PTH) level of 760 pg/mL. Elevated PTH in the presence of hyperphosphataemia and hypocalcaemia supports secondary hyperparathyroidism. This was further confirmed with visualization of hyperintense parathyroid glands on single photon emission computed tomography (SPECT). (Fig. 4) Although less frequent, other causes of calcinosis in ESRD include elevated calcium-phosphate product, elevated serum 1, 25 dihydroxycalciferol, aluminium intoxication in dialysis patients, high diasylate calcium exposure during dialysis. [2]

While renal osteodystrophy is primarily diagnosed with serum chemistry, radiologic findings are often the initial sign of disease. Also, there are distinct radiographic findings that contribute to the diagnosis of renal osteodystrophy, while excluding other diseases of calcinosis. Radiographs typically show amorphous, multilobular periarticular calcifications. This is also a common finding of tumoral calcinosis, which is largely considered indistinguishable from renal osteodystrophy on X-ray. [3] Tumoral calcinosis is a hereditary disease of phosphate metabolic dysfunction that involves normal calcium levels. However, radiographic evidence of osseous erosion is common in renal osteodystrophy, while uncharacteristic of tumoral calcinosis. [3] These osseous erosions are often present in subchondral bone at articulating joints and tendinous or ligamentous insertions. [1] Myositis ossificans was another plausible diagnosis with trauma to the patient’s shoulder. However, calcinosis typically takes several weeks to present on X-ray and there are no associated serum chemistry abnormalities. [3] CT findings of periarticular calcification are analogous to X-ray with CT providing better demarcation of the lesions. [4]

Treatment options for renal osteodystrophy range from conservative treatment with phosphate depletion or Vitamin D supplementation to parathyroidectomy, which this patient underwent at a later date. [4] Surgical excision of the periarticular calcifications is an option but is often avoided due to high recurrence. Efficient medical treatment usually results in resolution of periarticular and vessel calcification. [1]

Differential Diagnosis List

Final Diagnosis

Renal osteodystrophy

URL:	https://eurorad.org/case/14588
DOI:	10.1594/EURORAD/CASE.14588
ISSN:	1563-4086