A variety of conditions can lead to thinning or missing hair on the top of the head, and on presentation to a hospital, an experienced dermatologist can make an initial judgement based on the distribution of hair and how the scalp behaves. Typical androgenetic alopecia and baldness can usually be diagnosed without further examination.
However, for very early androgenic baldness, atypical baldness or thinning hair, a dermoscopy is required to allow a more detailed visualisation of the hair, follicular opening and scalp. If ringworm is suspected, fungal microscopy is required.
Difficult hair loss disorders also require a pathological examination of the scalp histology. Blood tests are also required when there is suspicion of association with connective tissue disease, syphilis, nutritional deficiencies or endocrine disorders.