Background: Heart failure is a condition with diverse aetiology and pathogenesis. This is associated with higher rates of comorbidities, such as i.e. hypertension, atrial fibrillation chronic kidney disease, anaemia and iron deficiency. The purpose of this study was to characterise patients hospitalised due to acutely decompensated heart failure, with a particular emphasis on any comorbidities and laboratory test abnormalities. Material and methods: A total of 102 patients aged over 18 years, hospitalised due to acute decompensated heart failure. Thorough medical history (including any concomitant diseases) was obtained from all patients. They also underwent a clinical examination and biochemical tests. Results: The subjects included were mostly men (76.5%) with ischemic aetiology (63.7%). The most common comorbidity was hypertension (66.6%), while hypotension affected only 2% of patients. The most common heart failure subtype was heart failure with reduced ejection fraction (60.8%). The detected blood test abnormalities included elevated cystatin C levels in 94.7%, hyperuricaemia in 75.5%, anaemia in 55.9%, and iron deficiency in 78.3% of patients. Conclusion: Most of acute decompensated heart failure patients suffer from comorbidities with a documented impact on prognosis. Cardiovascular decompensation poses a risk of multi-organ dysfunction and estimating its actual consequences requires a detailed assessment of complex laboratory tests, including levels of creatinine, cystatin C, uric acid, red blood cell parameters and iron metabolism parameters.