The substantial weight loss should also alert someone about a possible malignant process, as it is commonly associated.
The possibility of inflammatory lower back disease also should not be ruled out, as diseases like rheumatoid arthritis or ankylosing spondylitis can be rarely localized to the spine as well. Weight loss can also be a non-specific finding. Thus inflammatory arthritis should be another group of disorders to be kept as part of the diagnosis.
The addition of several recent infections and being short of breath despite being a non-smoker adds another layer of possibilities. Recurrent recent infections (not mentioned if they were chest infections or not) can be associated with immune suppression, which is seen in hematological illnesses. Shortness of breath can be due to a variety of causes including lung diseases, severe anemia and even heart failure, which should be investigated further.
The substantial weight loss is seen in many chronic conditions and malignant conditions, which can be confirmed after making the diagnosis. The history is not classically suggestive of any illness in particular, and based on the differential diagnoses outlined in the history, clinical tests should be interpreted for accurately diagnosing the condition.
In view of the bone pain, the clinical chemistry can be helpful if there is bone destruction. Calcium levels (3.48 mmol/L) are elevated, which is indicative of a possible bone destructive process, which can be seen in a variety of conditions. In addition, alkaline phosphatase is raised when there is new bone formation, as typically seen in classical hypercalcaemia seen with solid tumours invading bone. Moreover, phosphate levels are normal, which rules out hyperparathyroidism as a cause. Liver damage can also raise alkaline phosopahatase levels, but in light of the above history, is not one of our differential diagnoses.
However, in this case, alkaline phosphatase is normal (94 IU/L) too , which raises the possibility that myeloma is the underlying cause. Few other causes of hypercalcaemia have normal phosphates and alkaline phosphate levels. The cause of hypercalcaemia in myeloma is however complex, and thought to be related to cytokine-driven increase in osteoclast activity.
In this case we should also have done full serum creatinine and electrolytes, as renal insufficiency is common in myeloma as well as itself a cause of hypercalcaemia itself. The urea levels are increased ( 14.0 mmol/L) which is some cause for concern, as it could be associated with renal insufficiency. Infact hypercalcaemia itself can cause renal insufficiency, and up to this point that could be considered as the working hypothesis. Bone pain is seen in up to 70 % of cases of myeloma, and is an important consideration even at this stage.
There are no clinical chemistry tests that can confirm the diagnosis of multiple myeloma, which can only be diagnosed with any certainty with the use of immunological markers as discussed below.
Blood counts and film analysis
The Hb level of 10.7 g/dL shows that there is mild anaemia, although Mean Corpuscular Volume (MCV) is normal (82 fl) (normochromic anaemia) and so is the White cell count (11.7 x 109/L). Mild anaemia rarely