Final answer:
The abnormal finding in a toddler that a nurse should consider is cyanotic nailbeds, which can indicate serious health issues. Lumbar lordosis and a protruding abdomen are normal developmental observations.
Step-by-step explanation:
A nurse assessing a toddler should be aware of typical physical developmental milestones as well as indicators of potential health issues. Among the options provided, the finding that should be considered abnormal for a toddler is 2) Cyanotic nailbeds. This refers to a bluish or purplish discolouration of the nail beds, which could indicate a problem with oxygenation or circulation, potentially a serious concern such as a heart defect or respiratory disorder.
The other options are considered normal findings in toddlers. Option 1) Lumbar lordosis is a natural curvature of the spine that develops as the toddler begins to walk. Option 3) A protruding abdomen is also typical in toddlers due to the natural positioning of their abdominal muscles and posture. Option 4) A convex lumbar curve is another term for lumbar lordosis, which is normal as previously mentioned.