What is the association between potassium levels in the body and Anorexia Nervosa?

Take two What kind of micronutrient is potassium? What relationship would it have with the heart? Do you think there is a connection between anorexia and potassium?

 Potassium is a micronutrient and an electrolyte  Infant RDI 0.4 g/day  Children RDI 3-4 g/day  Adult RDI 4.7 g/day  Breastfeeding RDI 5.1 g/day (Zieve,2009)

 All meats and fish  Soy products  Fruits: cantaloupe, banana, kiwi, avocado  Vegetables: broccoli, sweet potato, and tomatoes  Milk and yogurt  Nuts (Zieve,2010)

 Too little potassium in the body is called Hypokalemia  Too much potassium in the body is called Hyperkalemia (Zieve,2009)

 An eating disorder  Body Dimorphic  Obsession with weight and food  Starvation  Exercise excessively  Abuse laxatives and diuretics

 Intense fear of gaining weight  Distorted self image  Absence of menstrual cycle  Refusal to maintain body weight at healthy range (Dryden-Edwards, 2010)

 Death  Anemia  Bone loss  Kidney Problems  Brain damage  Heart failure or abnormal heart rhythm  Electrolyte abnormalities (Dryden-Edwards, 2010)

 Potassium is an electrolyte  Found in food sources  Anorexia patients lose potassium though weight regulation  Fatal electrical alterations of the heart

What is the association between potassium levels in the body and Anorexia Nervosa?

 To define several diagnostic and symptomatic groups and test them separately for their potassium levels  Anorexia with vomiting  Anorexia with vomiting and laxative abuse  Anorexia without vomiting

 Descriptive Epidemiological › Cross sectional survey  Examining causal factors associated with different anorexia and bulimic groups with Hypokalemia  Retrospective study

 397 patients with preexisting eating disorder  Klinik am Korso in Bad Oeynhausen, Germany  Subgroups based on complete symptomatology  Similarities in BMI, age, disease duration  Hypokalemic: < 3.4 mmol/l plasma potassium

 Descriptive  Inferential  Correlation tests

 Standard Deviation  Mean  Range  Median

 Mann-Whitney U test  Kruskal-Wallis test  Analysis of Variance test (ANOVA)  Post-hoc test (Scheffe’)

 Pearson’s two-tailed testing  Spearman’s correlation testing  Multiple linear regression  Stepwise Linear Regression (R2) › Standardized regression coefficient  Coefficient of determination

 Hypokalemia in purging anorexic (p = 0.001)  Hypokalemia in non-purging anorexic (p=0.82)  Higher frequency (p = 0.001)  Severity (p = 0.001)  Differences between anorexic subgroups (p = 0.001)

 Potassium levels and BMI (r) 0.27 (p=0.001)  Vomiting frequency, laxative abuse and potassium levels (r) (p = 0.005)  Mean potassium 2.8 mmol/l

Table 2. Potassium levels and hypokalemia proportion in the subgroups

 Number of participants  Internal Validity › Recall bias › Selection bias › Confounding variables

 Organization  External Validity › Results represent an entire population

 Hypokalemia more common in binging and purging anorexics  Potassium losses through stool, urine and vomit  Possibly other factors associated with potassium loss not tested

What is the association between potassium levels in the body and Anorexia Nervosa?

 To determine the medical effects of anorexia on a young population in terms of normal body function

 Descriptive Epidemiological study › Cross sectional › Prospective  Community dwelling adolescent girls › Anorexia with outpatient care vs. healthy adolescents  118 adolescent girls › 60 with DSM IV diagnosed anorexia › 58 healthy- no past history of eating disorder

 Referred by treatment programs in Boston, MA  Prospective data collection at baseline visit  Three month or more community dwelling  Biochemical › Potassium levels  Anthropometric › BMI

 Descriptive statistics  Inferential statistics

 Mean  Standard Deviation

 T-test  Univariate regression analysis › Correlation between variables  Stepwise regression analysis › Significant predictors

 Mean serum potassium levels higher in anorexic › AN: 3.8 +/- 0.3 mmol/l › Healthy: 3.6 +/- 0.2 mmol/l  no subject Hypokalemic › Serum potassium< 3.0 mmol/l  Two subjects with history of purging behavior

 Weakness in planning  No hypothesis stated  Limited external validity

 Comparability to the control and observed group  Diverse referrals decrease selection bias  Limited external validity › Caucasian Adolescent female specific

 Normal serum potassium levels  Higher in anorexic › Due to dehydration  Total potassium levels may still be low  Not at risk even with low BMI  Still at risk for cardiac abnormalities  No purging behaviors observed

What is the association between potassium levels in the body and Anorexia Nervosa?

 Potassium levels are influenced by Anorexia  Both suggested potential cardiac risk  Differences in studies › Set potassium level as Hypokalemic › Population studied

 Yes!  Both saw changes in extracellular potassium in the Anorexic populations

 More research in diverse groups  Identify relationship of purging and potassium levels  Identify other variables not accounted for  Measuring total potassium vs. only plasma