When the kidneys are not working properly, there may be other health problems that are related to CKD. A few related health issues may be as follow:

Anemia:
Anemia is a problem that can be caused by kidney disease. Having too few red blood cells is called anemia. Healthy kidneys make a hormone called erythropoietin (EPO) that directs the bone marrow to make red blood cells. Damaged kidneys may not make enough of this hormone. Symptoms may include weakness and tiredness. Your doctor may prescribe EPO shots. This shot works as a replacement of the hormone. An iron supplement may also be prescribed.
Hemoglobin and hematocrit are tests for anemia.

High Blood Pressure (Hypertension):
High blood pressure can be both a cause and a complication of CKD. In addition to keeping the right chemical and fluid balance, the kidneys make a hormone called renin. Renin helps control blood pressure. Sometimes the kidney disease can be the cause of high blood pressure.

Acidosis:
Kidneys also control the amount of acid in body.  Person with CKD may have too much acid in their body. This condition is called acidosis and may lead to many health problems.

Bone Disease:
Kidneys also keep the right level of calcium and phosphorus in the body. CKD may change calcium levels in the bone; this change is known as renal bone disease or renal osteodystrophy. This can cause the bones to become thin and weak and may break easily.
Phosphate binders are often used to reduce the effects of high blood phosphorus levels in the bones. A special form of vitamin D called calcitriol or similar product may be needed. It is important not to take your phosphate binders with your iron pills.
Take the iron on an empty stomach and the phosphate binders with food.