Please select the eligibility criteria that correspond to the clinical trial below.
Title: A Three-Period, 58-Week Safety and Efficacy Trial of KRX-0502 (Ferric Citrate) in Patients With End-Stage Renal Disease (ESRD) on Dialysis
Brief Summary: This is up to a 58 week study comparing ferric citrate to active control for 52 weeks in ESRD dialysis patients, and subsequently comparing ferric citrate to placebo for 4 weeks.


Options:
A: Inclusion Criteria:

1. Males or non-pregnant, non-breast-feeding females
2. Age ≥18 years
3. On thrice-weekly hemodialysis or on peritoneal dialysis for at least the previous three months prior to Screening
4. Serum phosphorus ≥6.0 mg/dL for study entry
5. Taking less than 3-18 pills/day of current phosphate binder
6. Willing to be discontinued from current phosphate binder(s) and initiated on ferric citrate
7. Willing and able to give informed consent
8. Life expectancy \>1 year

Exclusion Criteria:

1. Parathyroidectomy within six months prior to Screening
2. Actively symptomatic gastrointestinal bleeding or inflammatory bowel disease
3. History of multiple drug allergies or intolerances
4. History of malignancy in the last five years (treated cervical or non-melanomatous skin cancer may be permitted if approved by CCC)
5. Previous intolerance to oral ferric citrate
6. Intolerance to oral iron-containing products
7. Psychiatric disorder that interferes with the patient's ability to comply with the study protocol
8. Inability to tolerate oral drug intake
9. Intolerance to calcium acetate and sevelamer carbonate
10. Any other medical condition that renders the patient unable to or unlikely to complete the trial or that would interfere with optimal participation in the trial or produce significant risk to the patient
11. Receipt of any investigational drug within 30 days of Screening Visit (Visit 0)
12. Inability to cooperate with study personnel or history of noncompliance
13. Unsuitable for this trial per Investigator's clinical judgment.
B: Inclusion Criteria:

1. Patients with a GFR of \< 45 ml/min;
2. Intact serum PTH \> 37 pg/ml;
3. Age \> 35 years (both genders and all races);
4. Able to perform two three-week balance studies;
5. Not on oral calcium or vitamin D other than multi vitamin, or willing to stop calcium or vitamin D for one month prior to entry in the study (day 1 of first calcium balance period);
6. Female patients must be post-menopausal (defined as last menstrual period at least 12 months prior to screening visit) or surgically sterile by hysterectomy;
7. On stable doses of diuretics, bisphosphonates, anti-epileptics (except dilantin) for at least 2 months.

Exclusion Criteria:

1. Serious underlying systemic disease (including uncontrolled diabetes, lupus, hypertension, amyloid, etc);
2. Taking drugs that alter calcium and phosphate balance or homeostasis including high dose cholecalciferol or ergocalciferol (1000 U/day or 50,000U/ wk, respectively), active vitamin D metabolites, calcimimetics, PTH analogues in the last 30 days;
3. Taking drugs that the investigator feels will alter calcium balance;
4. Plan to initiate dialysis in the next six months;
5. Hypercalcemia defined as serum calcium \> 10.5 mg/dl;
6. Hyperphosphatemia defined as serum phosphate \>5.5mg/ml;
7. Intestinal disease that alters absorption or normal intestinal function including celiac disease, small bowel resection, bariatric surgery;
8. Smoking
C: Inclusion criteria:

1. Men or women of at least 18 years of age
2. Stable maintenance of hemodialysis 3 times per week for 3 months or greater
3. Controlled serum phosphate if under phosphate-binder therapy
4. Patient must either be on a stable phosphate binder dose and are willing to stop their phosphate binder therapy at the beginning of the study, or not have received any phosphate binder therapy for at least 4 weeks prior to screening

Exclusion criteria:

1. Patients who are on peritoneal dialysis
2. Patients who have a transplant or parathyroidectomy scheduled during the study
3. Clinically significant GI disorder
4. Unstable medical condition other than Chronic Kidney Disease
5. Patient is currently being treated with oral iron
6. History of hemachromatosis, or ferritin \> 1000 ng/mL
7. Transferrin saturation \> 60%
8. Uncontrolled hyperparathyroidism (iPTH \> 84.8 pmol/L) Other protocol-defined inclusion/exclusion criteria may apply
D: Inclusion Criteria:

* Men or women \> 18 years of age;
* Must have no dietary restriction that would preclude eating standardized meal (both a meat based and vegan option available)
* The subject has voluntarily signed and dated the most recent informed consent form approved by an Institutional Review Board (IRB).
* Must be able to chew gum for at least 60 minutes.
* Must have historical eGFR appropriate for the study.

Exclusion Criteria:

* Receiving or has received an investigational product (or is currently using an investigational device) within 30 days prior to Visit 2;
* Evidence of active (clinically significant) infection at the time of study enrollment (in the opinion of the investigator);
* Dental work within 48 hours of enrollment (Visit 2); and
* Known sensitivity to chitin, or allergy to shellfish

Answer: A