FGF23 and neoplasm: Finding the tumours can be a major diagnostic challenge and may involve total body magnetic resonance imaging (MRI); as tumours can occur anywhere in the body, it is important to scan the whole body, including extremities, which is often excluded in routine nuclear medicine imaging [44], computed tomography (CT), scintigraphy using radiolabelled somatostatin analogue (such as 99mTc-Tektrotyd) and positron emission tomography, with computed tomography: fluorodeoxyglucose (18F-FDG) PET/CT and galium (68Ga) DOTATATE PET/CT and selective venous sampling for FGF23 [44–51].