The results of this study confirms the effect of LSG in weight reduction, as similarly reported in previous literature (13,17,18,20,22,24,25). Our results show that nutritional deficiencies,especially iron, are very common in the post-LSG period.Another remarkable outcome of the current study is that the rates of not coming for follow-ups of patients are very high.
According to our data, as similar to the previous literature, 18.64% of the individuals had vitamin B12 deficiency in the preoperative period (12,14,16,24,30). The frequency of vitamin B12 deficiency started to decrease from the first year and it was significantly less common in the following years compared to preoperative values, but it was still more frequent than some other studies (10,16,19,24,31). Also some studies showed an acceleration in percantage of deficiency at first year post-LSG contrast to our study (14,16,19). We thought that in the postoperative period, vitamin B12 deficiency is seen less frequently than baseline may be related to the parenteral administration of vitamin B12 replacement.Because the cause of post LSG vitamin B12 deficiency is probably the decrease of intrinsic factor and this can be overcome with parenteral administration.Our post LSG vitamin B12 deficiency rates were also lower than the literature(13,18,23-25,30).On the contrary, there are studies showing that there is no vitamin B12 deficiency in a long-term period in post-LSG patients(17,20,32).
Folic acid deficiency is mainly caused by insufficient consumption of green leafy vegetables (14).We did not observe a noticeable folate deficiency neither at the beginning nor any follow up, similar to other mediterranen countries’ studies (23,24) but our percantages were lower than most of the studies (12,16,20,21,33). Only at first year after LSG we found that 8.73% of the individuals had folate deficiency and it was statistically significant increase compared to baseline.We thought that the increase in folate deficiency in the first year was related to poor food preferences rather and depleted stores than the procedure, because the proximal small intestine, the main absorption site of folic acid, is preserved in LSG surgery(10,14,31).This increase in the first year has been reported in other studies (14,20,21), but not all (12,16,33).We observed that the prevalence of folate deficiency in the visits after the first year was at preoperative levels. There are also studies reporting that folate deficiency decreases (13,20) or is never seen in long-term follow-up (17,20,23,24,32).
Serum Iron and Ferritin (storage iron) Deficiency
In LSG patients iron deficiency can be attributed to several reasons such as the decreased secretion of gastric hydrocloric acid because of the procedure (10,14,18), preoperative low ferritin levels (10), too much weight loss (10), not preffering oral iron supplements due to their gastrointestinal side effects and possible impact on weight regain, intolerances to red meat consumption and reduced appetite (18,34).Female sex and menstrual cycle are also risk factors for iron deficiency (10,12,16).
Iron deficiency is prevalent among individuals presenting for BS due to inadequate of iron intake,more iron requirement because of high blood volumes and low iron absorption due to low levels of chronic inflammation(35).In literature there is a conflict on iron deficiency definition in LSG patients. Both serum iron and ferritin levels are used to identify iron deficiency. It is still uncertain which ferritin level should be considered as a cutoff. Most of the studies were used low serum iron levels for defining iron deficiency (10,13,14,32,34).The prevalence of iron deficiency has been reported at rates ranging from 6.6% to 50.5%.Our results were consistent with the literature with a rate of 37.68%(12-14,17,23,24). We also observed a downward trend in patients with low serum iron during follow-up visits.This may be explained by taking supplements postoperatively (36).
The other studies in literature were used serum ferritin levels to identify iron deficiency (21,25,32,37,38). Ferritin is an indicator forstorage iron so it will be a better parameter for iron deficiency (29). But because of the low grade chronic inflammation in patients with obesity ferritin levels could be found false high (29,39-41). Due to postoperative weigt loss inflammation disappears and ferritin levels drop as expected (41). Inflamation affects the diagnostic value of ferritin(29,39,40). As a acute phase reactant ferritin level <40 ng/ml should be considered as a deficiency (42). If cut off take as 12-15 ng/ml spesifite is 99% but sensitivite is 57%, when it takes as 30 ng/ml sensitivite rises 92% (43). Because of these wide cutoff range, study results were all different in literature (12,17,18,21,23-25,32,37,38,44).
We evaluated our data in both cutoffs. As expected, when <30 ng / mL was taken as cutoff, more patients had hypoferritinemia than <15 cutoff.Hypoferritinemic patients significantly increased in postoperative visits compared to preopretive in both cutoff values.While the effects of iron or iron supplements taken orally appear on serum iron level immediately, there is no acute effect on ferritin level.In the postoperative visits, while the rate of patients with low serum iron decreases, the increase ofthe rate of patients with hypoferritinemia may be due to oral iron or supplements containing iron.There was no significant difference in %EWLbetween patients with and without hypoferritinemia at follow-up.Therefore, we cannot say that the increase in the frequency of hypoferritinemia is a simple result of improvement in low-grade inflammation associated with obesity due to weight loss.Interestengly, there was a negative but statistically unsignificant relationship between ferritin and %EWL in follow-up visits. However, we also found that concurrently anemia ratio was also increased and anemic patients had hypoferritinemia and lower serum iron levels. Therefore, we can think that the change in the ferritin level reflects the change in the iron state rather than a simple result of the change in the inflammation state. When we consider that anemic and hypoferritinemic patients lose more weight, we can conclude that this group of patients pay more attention to their diets with fear of gaining weight again and do not use iron or iron supplements regularly or receive insufficient dose replacement. Considering that the majority of patients in our study are premenopausal women,it is possible that changes in weight loss and menstrual status may also play a role in the increase frequency of anemia and hypoferritinemi.
Anemia
Hemoglobine is the only indicator for defining anemia (28). In our study we found 24,85% of the patients had anemia and they were all women. In our study, no anemic male patient was detected in preoperative and postoperative follow-up visits.Although anemia is more common in women in the literature, in two studies preoperative anemia ratio was found higher in men (45,46). During our study we did not find any statistically significant changes in percanteges of anemic patients (10,24,41). Our ratio was mostly higher than other studies, especially at long- term period after LSG (17,18,20,21,23,38) but lower than two studies (24,41).
Compliance and Supplement Choices
The first year compliance rates, which were around 50-60% in our study, were consistent with the other study results, but this rate decreased further in the long-term follow-up(13,17,20-22,25).
There was no significant difference in terms of any vitamin deficiency or frequency of anemia in those who used or did not use supplements during follow-up visits.Although the rates of patients receiving vitamin B12 and iron replacement were similar, there was a decrease in vitamin B12 deficiency and an increase in iron deficiency in follow-up visits.As a consequence it seems reasonable to recommend higher doses or IM/IV modules for treating iron deficiency and compliance should be stimulated.In our study, the decrease in frequency after the increase in folate deficiency in the first year may be due to both the procedure applied and the nutritional properties of our country.In the Mediterranean country where fruits and greens are not missing from the kitchen, green vegetables and fruits cannot be consumed sufficiently in the first year due to the process applied.
Unfortunately there is no consensus on the optimal supplement levels and treatment duration in literature (10,14,16,17,21,30,47,48) but still IFSO and ASMBS recommend for a long term supplementation after BS (49,50).
Limitations
The retrospective nature of our study was the most important limitation. Especially in the patient population where there was a significant number of female patients, we did not know the menstruation scheme and supplement usage before operation. We did not follow other acute phase reactants in order to control hyperferritinemia due to inflammatory status.
We did not question the frequency of nausea and vomiting that caused folic acid deficiency in the first year. Also we did not analyze the PPI usage rates in terms of iron and vitamin B12 deficiency that may occur due to regular use. The fact that, deficiencies in the desired blood tests in the control visits, verbal evaluation based on patient compliance; it could contribute to results.