Congenital adrenal steroidogenesis disorders are rare diseases that can lead to life-threatening conditions in newborns, primarily salt-wasting syndrome and adrenal crisis. It is therefore essential for paediatricians and family physicians to be familiar with the symptoms suggestive of steroidogenesis defects, such as failure to thrive, vomiting, dehydration, electrolyte imbalances, and abnormal appearance of external genitalia. Early initiation of diagnostic procedures enables the prompt introduction of appropriate hormonal replacement therapy. However, the diagnostic process is not straightforward and requires consideration of other rare causes of the disease, which often present with similar but diverse clinical, biochemical, and hormonal features. A normal result of a screening test assessing 17-hydroxyprogesterone levels does not rule out rare causes of steroidogenesis disorders, which should be considered in the differential diagnosis when the aforementioned symptoms are present. This report discusses three newborns: one diagnosed with congenital adrenal hyperplasia due to 11β-hydroxylase deficiency, and two with aldosterone synthase deficiency.