“Common diseases that cause thickening of the toenails are.
The most common cause of thickened toenails is nail fungus, or ‘grey nails’, which can also be associated with diseases such as ringworm, nail psoriasis, congenital thick nail disease and diabetic skin disease.
Fungal infections can occur when the fungus invades the toenail and if the toenail is in an environment conducive to fungal growth or has a low resistance, the infection is easily triggered and the fungus invades the surrounding skin and nail plate, affecting the growth of the nail and promoting the accumulation of keratinous material around it, causing the nail to thicken.
Congenital thick nails are caused by a genetic mutation and are a hereditary disease, most often seen in newborn children. They are characterised by thickening, yellowing or even browning of all the toenails, with papules and patches on the elbows, knees and hips. It needs to be treated under medical supervision to determine the cause of the disease.”