The aim of this paper was to evaluate the possibility of detecting metabolic problems and mastitis using milk components in dairy cows in early lactation. Experimental monitoring was conducted in two dairy farms from 2021 to 2022. The results showed that increasing fat-to-protein ratio (FPR) in milk and increasing milk octadecenoic acid (C18:1) helped to detect dairy cows at risk of developing negative energy balance (NEB). Clinical signs of subacute ruminal acidosis (SARA) were relatively well reflected in low FPR values. Lactose content appeared to be a good indicator of mastitis and may be helpful in identifying animals at risk for NEB. However, the results also showed the substantial difficulty in estimating threshold values for individual health problems. Clearly, changes in individual milk components over time rather than absolute values are more useful for interpreting the results and describing the metabolic status of animals.