Treatment of iron deficiency anemia associated with gastrointestinal tract diseases

Table 1 Causes of iron deficiency anemia stemming from the GI tract

Decreased iron uptake	Increased iron loss (bleeding into GI tract)
Celiac sprue	Esophagus (esophagitis and cancer)
Giardiasis	Stomach (ulcer, gastritis, cancer, vascular lesions)
Achlorhydria (due to atrophic gastritis, H. pylori infection…)	Small bowel (vascular lesions)
Gastrojejunostomy and other surgical techniques bypassing the duodenum where iron absorption is maximal	Large bowel (cancer, angioectasias, adenoma, colitis)
Short bowel syndrome

GI: Gastrointestinal; H. pylori: Helicobacter pylori.

Table 2 Pros and cons of parenteral iron over oral iron therapy

Pros

Assured repletion of iron stores regardless of factors affecting iron absorption

Rapid reversal of iron deficiency

Certain or at least assessable adherence to therapy

Infrequent side effects

One-time administration (FeCarb & LMWID)

Cons

Rare lethal drug-related adverse events

Expensive

Requires facilities/staff for administration

Simply taking tablets may be more convenient for some patients

FeCarb: Ferric carboxymaltose; LMWID: Low-molecular weight iron dextran.

Table 3 Selected characteristics and dosage guidelines of parenteral iron complexes

	LMWID	Iron gluconate	Iron sucrose	FeCarb
Concentration	50 mg/mL (2 mL vial)	12.5 mg/mL (5 mL ampule)	20 mg/mL (5 mL vial)	50 mg/mL (2 mL vial)
IV injection dose	100 mg over 2-5 min	125 mg over 10 min	100 mg over 5 min	100 mg over 2 min
Direct iron donation to transferrin	1-2	5-6	4-5	1-2
Test dose required	Yes, 25 mg slow IV push	No	No	No
Maximal single dose for IV infusion	Not limited	125	500	1000
Total dose infusion	Yes, in NS over 1-6 h	No	No	No
Pregnancy category	C	B	B	N/A
Life threatening ADEs (per 106 doses)	3.3	0.9	0.6	N/A

LMWID: Low molecular weight iron dextran; IV: Intravenous; ADE: Adverse drug event; NS: Normal saline; N/A: Not available.

Table 4 Clinical studies comparing parenteral and oral iron therapy

Author	Intervention	Study method	n	Efficacy	P
Schröder et al[33]	Elemental iron 100-200 mg/d × 6 wk	Randomized	24	1RR: 53%	0.85
	Iron sucrose 7 mg/kg × one dose then 200 mg once-twice/wk × 5 wk		22	1RR: 55%
Erichsen et al[34]	Elemental iron 120 mg/d × 14 d	Crossover trial with a washout period of > 6 wk	17	Mean increase in Hb: 0.2	< 0.05
	Iron sucrose 200 mg on days 1, 5, 10		17	Mean increase in Hb: 0.7
Kulnigg et al[28]	Elemental iron 200 mg/d × 12 wk	2:1 (FeCarb:oral) randomization	136	Median increase in Hb: 2.8	NS
	FeCarb 1000 mg (max) weekly (× 1-3 wk)		60	Median increase in Hb: 3.7
Gisbert et al[35]	Elemental iron 106 mg/d × 3-6 mo	Hb ≥ 10.0 g/dL	78	2RR: 89%	NS
	Iron sucrose 200 mg twice/wk × 3-6 mo	Hb < 10.0 g/dL	22	2RR: 77%
Lindgren et al[36]	Elemental iron 200 mg/d × 20 wk	Randomized	46	1RR: 47%	0.07
	Iron sucrose 200 mg weekly until calculated dose reached		45	1RR: 66%

¹Increase in Hb ≥ 2.0 g/dL;

²Complete normalization of Hb. RR: Response rate.