Vitamin D deficiency: Mild elevation of alkaline phosphatase (ALP) can be seen in vitamin D deficiency, which is common in young adults, especially during winter months or in individuals with limited sun exposure and inadequate dietary intake.

Pregnancy: Even if the patient is not aware of her pregnancy, it can cause an elevation in ALP levels due to the production of placental ALP.
Osteomalacia: Though less common, osteomalacia (softening of the bones) can cause an elevation in ALP and might not present with significant symptoms early on.
Hypothyroidism: Mild elevations in ALP can be associated with hypothyroidism, possibly due to the effect of thyroid hormones on bone metabolism.

Bone metastasis: Although rare in a young adult, bone metastasis from a malignancy like breast cancer can cause an elevation in ALP. It's crucial to consider this, especially if there's any family history or other risk factors.
Primary biliary cirrhosis: This autoimmune disease of the liver can cause an elevation in ALP. Early detection is crucial for management and prognosis.
Wilson's disease: A genetic disorder leading to copper accumulation in the liver and other organs, which can cause liver dysfunction and elevated ALP.

Paget's disease of bone: A condition characterized by an abnormal breakdown and regrowth of bone tissue, leading to deformity. It's rare in young adults but can cause significant elevation in ALP.
Fibrous dysplasia: A disorder where normal bone and marrow are replaced with fibrous tissue, leading to formation of weakened bones and potentially elevated ALP levels.
Hyperparathyroidism: Primary hyperparathyroidism can lead to elevated ALP due to increased bone turnover, though it's less common in young asymptomatic individuals.