Anemia and iron deficiency in gastrointestinal and liver conditions

Table 1 Overview of diseases considered to be associated with iron deficiency/iron deficiency anemia

Conditions	Anemia or IDA prevalence	Predominant pathological contributors to anemia			Association with anemia and ID
		Bleeding	Malabsorption	Inflammation
Nonvariceal upper GI bleeding[33]	80%	√			> 80% of patients admitted to hospital with nonvariceal AUGIB were anemic at the time of discharge
Celiac disease[87-89]	32%-69%		√	√	Well-established relationship between celiac disease and IDA
					Most widely cited cause of IDA is abnormal iron absorption, but bleeding and inflammation are also known contributory factors
Intestinal parasitic infections[151]	33%-61%	√	√		T. trichiura and hookworm infections are closely associated with IDA
GI cancers[107,108,111,117,121-120]	50%-60%	√		√	CRC: IDA associated with greater tumor diameter and with cancers of the right side of the colon
					Polyps: IDA much more common with malignant polyps than benign polyps
					GIST: Most frequent presentation is GI bleeding, which can result in anemia. In pediatric GIST, anemia is the most frequent clinical finding
					Gastric cancers: 6.8-fold relative risk of gastric cancer in patients with Pernicious anemia
					Small bowel malignancies: Anemia among most common presenting symptoms
					Esophageal cancers: Patients with Fanconi anemia at increased risk
Esophagitis and hiatal hernia[23-26]	8%-42%	√			Gastric bleeding from hernia is an established cause of IDA
					Even in absence of visible lesions, large hernia may be a possible cause of IDA with unexplained etiology
Bariatric surgery[77,196]	10%-40%		√		ID and anemia are well-known risks after bariatric procedures, but causes are multifactorial and vary depending on exact procedure and patient population
Intestinal failure[101-103]	30%-37%	√	√		Intestinal failure is associated with ID due to malabsorption, GI blood loss, and multiple surgery
Diverticular disease[144]	25%	√			One of the most common causes of lower GI bleeding leading to IDA
					Increasing prevalence due to rise in elderly population
Restorative proctocolectomy[153]	6%-21%	√	√		IDA due to mucosal bleeding and impaired iron absorption in patients developing symptomatic or asymptomatic pouchitis
NSAID-associated fecal blood loss[1]	10%-15%	√			Even low dose aspirin and non-aspirin-NSAIDs increase mean fecal blood loss 2-4-fold compared with normal
Angiodysplasia[1]	5%	√			Most common cause of lower GI bleeding in the elderly
Gastric antral vascular ectasia (GAVE)[1,48,55]	1%-2%	√			Chronic, slow bleeding is typically associated with IDA
Gastritis[57,66]	NA		√	√	H. pylori infection suggested to play important role in development of IDA
Peptic ulcer[197]	NA		√	√	H. pylori infection and IDA as above. Additionally, bleeding from ulcer
Chronic hepatitis and liver conditions with GI bleeding[155]	75%	√			Chronic liver disease can be complicated by anemia, particularly due to bleeding
Non-alcoholic fatty liver disease (NAFLD)[171]	NA			√	One-third of adult NAFLD subjects are reported to be iron deficient, defined by a TSAT < 20%

H. pylori: Helicobacter pylori; AUGIB: Acute upper gastrointestinal bleeding; CRC: Colorectal cancer; GI: Gastrointestinal; GIST: Gastrointestinal stromal tumors; ID: Iron deficiency; IDA: Iron deficiency anemia; NA: Not available.

Table 2 Estimated total iron deficit (mg elemental iron) based on hemoglobin and body weight

Degree of iron deficiency	Hemoglobin level (g/dL)	Iron deficit (mg)
		Body weight	Body weight
		< 70 kg	≥ 70 kg
Moderate	10-12 (women)	1000	1500
	10-13 (men)
Severe	7-10	1500	2000
Critical	< 7	2000	2500

Simplified scheme for estimation of total iron requirements[6].