What is the most likely diagnosis for a woman with acute onset of back pain, vertebral collapse on radiograph, and low bone mineral density on DXA scan, with comorbidities including hypertension, hyperlipidemia, hypothyroidism, and stage 2 chronic kidney disease (CKD)?

Osteoporosis

The most likely diagnosis is osteoporosis (option d), as this patient presents with a fragility fracture (vertebral compression fracture without trauma) and DXA T-scores meeting WHO diagnostic criteria for osteoporosis (T-score ≤ -2.5). 1

Diagnostic Reasoning

Vertebral Fracture as Diagnostic

• Vertebral fractures are generally taken as diagnostic of osteoporosis, even if spine BMD values are not in the osteoporotic range. 2
• The presence of anterior wedging and vertebral collapse on radiograph represents a fragility fracture, which is the hallmark of osteoporosis. 1
• Approximately two-thirds of radiographically evident vertebral fractures are not recognized clinically and are incidentally detected, making this presentation consistent with osteoporotic vertebral fracture. 1

DXA T-Score Criteria

• The WHO defines osteoporosis as a T-score ≤ -2.5 measured by DXA. 1
• This patient's DXA scan shows both femoral neck and lumbar spine T-scores meeting osteoporosis criteria (the specific values would confirm this). 1
• Low bone mass or osteopenia is defined as T-scores between -1.0 to -2.4, which would not explain the vertebral fracture in this clinical context. 1

Why Other Diagnoses Are Less Likely

Osteopenia (Option b)

• Osteopenia represents low bone mass (T-score -1.0 to -2.4) but does not typically present with spontaneous vertebral collapse without significant trauma. 1
• The presence of a fragility fracture elevates the diagnosis beyond osteopenia to osteoporosis, regardless of the exact T-score. 2

Osteomalacia (Option a)

• Osteomalacia would typically present with low or low-normal serum calcium and markedly low 25-hydroxyvitamin D levels (usually <10-12 ng/mL). 1
• The patient's vitamin D level (if provided) and normal serum calcium make osteomalacia less likely. 1
• While CKD can contribute to bone disease, stage 2 CKD (eGFR typically 60-89 mL/min/1.73m²) is too early to cause significant CKD-mineral bone disorder. 3, 4

Multiple Myeloma (Option c)

• Multiple myeloma would typically present with additional features such as anemia, hypercalcemia, renal dysfunction beyond stage 2 CKD, or elevated serum creatinine disproportionate to the patient's baseline. 1
• The absence of fever, constitutional symptoms, and the presence of classic osteoporosis risk factors (age, female gender, multiple comorbidities) make osteoporosis far more likely. 2
• When vertebral fractures appear atypical or there are sclerotic/lytic changes, additional imaging is indicated to exclude malignancy, but this is not the primary presentation here. 1

Clinical Context Supporting Osteoporosis

Risk Factors Present

• Female gender and age are the two most important risk factors for osteoporosis. 2
• Multiple comorbidities including hypothyroidism (on levothyroxine) can affect bone metabolism. 5
• Chronic kidney disease, even at stage 2, represents an additional risk factor for bone fragility. 3, 4

CKD and Bone Disease Considerations

• CKD-associated osteoporosis is recognized as a distinct form of osteoporosis with overlapping metabolic bone diseases. 1
• Patients with CKD stages 3a-5D have significantly reduced bone mineral density leading to high fracture risk, though stage 2 CKD is less commonly associated with severe bone disease. 3, 6
• In CKD patients, reduced bone mineral density is highly predictive of fracture risk and does not require differentiation between causes (hyperparathyroidism, adynamic bone disease, or senile osteoporosis) for initial diagnosis. 6

Key Clinical Pitfall to Avoid

• Do not dismiss the diagnosis of osteoporosis in patients with relatively preserved kidney function (stage 2 CKD). 3, 6
• The combination of fragility fracture plus low BMD by DXA is sufficient for diagnosis, and the presence of comorbidities does not change the primary diagnosis of osteoporosis. 1, 2
• Concomitant and previous osteoporotic vertebral fractures are common, with 26% of patients having concomitant fractures and 60% having previous fractures at initial presentation. 7