Why do CKD Patients Have a Poor Appetite?
Poor appetite is common in patients with chronic kidney disease (CKD), and these symptoms worsen as the disease progresses. The continuous decline of the glomerular filtration rate in CKD patients is associated with a significant reduction in food intake. Around one-third of chronic dialysis patients complain of a fair or poor appetite. And this is directly related to poor patient outcomes. A close association between appetite, malnutrition, and inflammation has been reported in patients undergoing hemodialysis.
Leptin inhibits food intake, stimulates energy expenditure, and modulates the activity of nitric oxide synthase (NOS). 28-amino acid peptide ghrelin, synthesized principally in the stomach is responsible for increasing food intake and body weight. Lower levels of acyl ghrelin and obestatin are found in Hemodialysis patients. Increased PTH levels also influence the appetite negatively.
Appetite Regulation
The factors influencing food intake are complex it involves metabolic signals (hunger and satiety). The hunger center is in the lateral hypothalamus containing dopaminergic neurotransmitters. The satiety center is in the ventromedial hypothalamus containing serotoninergic and adrenergic neurotransmitters.
The Consequences
Protein energy wasting is associated with adverse clinical outcomes, such as increased rates of hospitalization and death.
Counselling
Trained dietitians play a central role in helping patients and their families with food choices, meal schedules, and healthful eating habits.
Medications
Appetite stimulants, including megestrol, dronabinol, mirtazapine, and cyproheptadine, as adjunctive treatment options in addition to parenteral or oral nutritional supplementation, are recommended by The International Society of Renal Nutrition and Metabolism for CKD patients.
Increased PTH levels in patients with CKD are also associated with poor appetite. Calcium sensing receptor agonists like Cinacalcet are effective in reducing PTH value.
In patients in whom preventive measures in dietary intake, nutritional supplementation, administered orally, enterally, or parenterally, is effective in replenishing protein and energy stores and helps maintain adequate nutritional status. Alpha keto-analogs are helpful in protein deficiency.
In patients with ESRD on dialysis, there are protein catabolic processes, such as the unavoidable loss of amino acids (6–8 g per HD session) and albumin into the dialysate. IV amino acid supplements such as pure crystalline amino acid solution are highly beneficial without discomfort for HD patients.