Renal osteodystrophy may exhibit no symptoms; if it does show symptoms, they include:

- Bone pain

- Joint pain

- Bone deformation

- Bone fracture

- The broader concept of chronic kidney disease-mineral and bone disorder (CKD-MBD) is not only associated with fractures but also with cardiovascular calcification, poor quality of life and increased morbidity and mortality in CKD patients (the so-called bone-vascular axis). These clinical consequences are acquiring such an importance that scientific working groups (such as the ERA-EDTA CKD-MBD Working Group) or international initiatives are trying to promote research in the field including basic, translational and clinical research.

Renal osteodystrophy is currently defined as an alteration of bone morphology in patients with chronic kidney disease (CKD). It is one measure of the skeletal component of the systemic disorder of chronic kidney disease-mineral and bone disorder (CKD-MBD). The term "renal osteodystrophy" was coined in 1943, 60 years after an association was identified between bone disease and renal failure. The traditional types of renal osteodystrophy have been defined on the basis of turnover and mineralization as follows: mild, slight increase in turnover and normal mineralization; osteitis fibrosa, increased turnover and normal mineralization; osteomalacia, decreased turnover and abnormal mineralization; adynamic, decreased turnover and acellularity; mixed, increased turnover with abnormal mineralization. A Kidney Disease: Improving Global Outcomes report has suggested that bone biopsies in patients with CKD should be characterized by determining bone turnover, mineralization, and volume (TMV system). On the other hand, CKD-MBD is defined as a systemic disorder of mineral and bone metabolism due to CKD manifested by either one or a combination of the following: 1) abnormalities of calcium, phosphorus, PTH, or vitamin D metabolism; 2) abnormalities in bone turnover, mineralization, volume, linear growth, or strength (renal osteodystrophy); and 3) vascular or other soft-tissue calcification.

The major symptoms of OFC are bone pain or tenderness, bone fractures, and skeletal deformities such as bowing of the bones. The underlying hyperparathyroidism may cause kidney stones, nausea, constipation, fatigue and weakness. X-rays may indicate thin bones, fractures, bowing, and cysts. Fractures are most commonly localized in the arms, legs, or spine.

The addition of weight loss, appetite loss, vomiting, polyuria, and polydipsia to the aforementioned symptoms may indicate that OFC is the result of parathyroid carcinoma. Parathyroid carcinoma, an uncommon cancer of the parathyroid glands, is generally indicated by serum calcium levels higher than usual, even in comparison to the high serum calcium levels that OFC generally presents with. Symptoms are also often more severe. Generally, the presence of a palpable neck mass is also indicative of the cancer, occurring in approximately 50% of sufferers, but virtually nonexistent in individuals with OFC with a different origin.

Chronic kidney disease–mineral and bone disorder (CKD-MBD) is one of the many complications associated with chronic kidney disease. It represents a systemic disorder of mineral and bone metabolism due to CKD manifested by either one or a combination of the following:

- Abnormalities of calcium, phosphorus (phosphate), parathyroid hormone, or vitamin D metabolism

- Abnormalities in bone turnover, mineralization, volume, linear growth, or strength

- Vascular or other soft-tissue calcification

CKD-MBD explains, at least in part, the high morbidity and mortality of CKD patients, linking kidney and bone disease with cardiovascular complications. It is a matter of discussion whether CKD-MBD may be considered a real syndrome or not.

CKD-MBD broadens the "old" concept of "renal osteodystrophy", which now should be restricted to describing the "bone pathology" associated with CKD. Thus, renal osteodystrophy is currently considered "one" measure of the skeletal component of the systemic disorder of CKD–MBD that is quantifiable by histomorphometry of bone biopsy.

Osteitis fibrosa cystica is defined as the classic skeletal manifestation of advanced hyperparathyroidism. Under the ICD-10 classification system, established by the World Health Organization, OFC is listed under category E21.0, primary hyperparathyroidism.

Nephrocalcinosis, once known as Albright's calcinosis after Fuller Albright, or Anderson-Carr kidneys, is a term originally used to describe deposition of calcium salts in the renal parenchyma due to hyperparathyroidism. The term nephrocalcinosis is used to describe the deposition of both calcium oxalate and calcium phosphate. It may cause acute kidney injury. It is now more commonly used to describe diffuse, fine, renal parenchymal calcification on radiology. It is caused by multiple different conditions and is determined progressive kidney dysfunction. These outlines eventually come together to form a dense mass. During its early stages, nephrocalcinosis is visible on x-ray, and appears as a fine granular mottling over the renal outlines. It is most commonly seen as an incidental finding with medullary sponge kidney on an abdominal x-ray.

However, it may be severe enough to cause (as well as be caused by) renal tubular acidosis or even end stage renal failure, due to disruption of the renal tissue by the deposited calcium.

Though this condition is usually asymptomatic, if symptoms are present they are usually related to the causative process, (e.g. hypercalcemia). Some of the sympotoms that can happen are blood in the urine, fever and chills, nausea and vomiting, severe pain in the belly area, flanks of the back, groin, or testicles.

These include renal colic, polyuria and polydipsia:

- Renal colic is usually caused by pre-existing nephrolithiasis, as may occur in patients with chronic hypercalciuria. Less commonly, it can result from calcified bodies moving into the calyceal system.

- Nocturia, polyuria, and polydipsia from reduced urinary concentrating capacity (i.e. nephrogenic diabetes insipidus) as can be seen in hypercalcemia, medullary nephrocalcinosis of any cause, or in children with Bartter syndrome in whom essential tubular salt reabsorption is compromised.

There are several causes of nephrocalcinosis that are typically acute and present only with renal failure. These include tumor lysis syndrome, acute phosphate nephropathy, and occasional cases of enteric hyperoxaluria.

Osteodystrophy is any dystrophic growth of the bone. It is defective bone development that is usually attributable to renal disease or to disturbances in calcium and phosphorus metabolism.

One form is renal osteodystrophy.

Signs and symptoms include ectopic calcification, secondary hyperparathyroidism, and renal osteodystrophy. Abnormalities in phosphate metabolism such as hyperphosphatemia are included in the definition of the new chronic kidney disease-mineral and bone disorder (CKD-MBD).

Symptoms depend on whether the hyperparathyroidism is the result of parathyroid overactivity or secondary.

In primary hyperparathyroidism about 75% of people have no symptoms. The problem is often picked up during blood work for other reasons via a raised calcium. Many other people only have non-specific symptoms. Symptoms directly due to hypercalcemia are relatively rare, being more common in patients with malignant hypercalcemia. If present, common manifestations of hypercalcemia include weakness and fatigue, depression, bone pain, muscle soreness (myalgias), decreased appetite, feelings of nausea and vomiting, constipation, polyuria, polydipsia, cognitive impairment, kidney stones (See Foot Note) and osteoporosis. A history of acquired racquet nails (brachyonychia) may be indicative of bone resorption. Parathyroid adenomas are very rarely detectable on clinical examination. Surgical removal of a parathyroid tumor eliminates the symptoms in most patients.

In secondary hyperparathyroidism the parathyroid gland is behaving normally; clinical problems are due to bone resorption and manifest as bone syndromes such as rickets, osteomalacia and renal osteodystrophy.

Hyperphosphatemia is an electrolyte disturbance in which there is an abnormally elevated level of phosphate in the blood. Often, calcium levels are lowered (hypocalcemia) due to precipitation of phosphate with the calcium in tissues. Average phosphorus levels should be between 0.81 mmol/litre and 1.45 mmol/litre.

Secondary hyperparathyroidism is due to physiological (i.e. appropriate) secretion of parathyroid hormone (PTH) by the parathyroid glands in response to hypocalcemia (low blood calcium levels). The most common causes are vitamin D deficiency (caused by lack of sunlight, diet or malabsorption) and chronic kidney failure.

Lack of vitamin D leads to reduced calcium absorption by the intestine leading to hypocalcemia and increased parathyroid hormone secretion. This increases bone resorption.

In chronic kidney failure the problem is more specifically failure to convert vitamin D to its active form in the kidney. The bone disease in secondary hyperparathyroidism caused by renal failure is termed renal osteodystrophy.

The buildup of oxalate in the body causes increased renal excretion of oxalate (hyperoxaluria), which in turn results in renal and bladder stones. Stones cause urinary obstruction (often with severe and acute pain), secondary infection of urine and eventually kidney damage.

Oxalate stones in primary hyperoxaluria tend to be severe, resulting in relatively early kidney damage (say teenage, early adulthood), which impairs the excretion of oxalate leading to a further acceleration in accumulation of oxalate in the body.

After the development of renal failure patients may get deposits of oxalate in the bones, joints and bone marrow. Severe cases may develop haematological problems such as anaemia and thrombocytopaenia. The deposition of oxalate in the body is sometimes called "oxalosis" to be distinguished from "oxaluria" which refers to oxalate in the urine.

Renal failure is a serious complication requiring treatment in its own right. Dialysis can control renal failure but tends to be inadequate to dispose of excess oxalate. Renal transplant is more effective and this is the primary treatment of severe hyperoxaluria. Liver transplantation (often in addition to renal transplant) may be able to control the disease by correcting the metabolic defect.

In a proportion of patients with primary hyperoxaluria type 1 (about 5%), pyridoxine treatment (vitamin B6) may decrease oxalate excretion and prevent kidney stone formation.

Primary hyperoxaluria is an autosomal recessive disease, meaning both copies of the gene contain the mutation. Both parents must have one copy of this mutated gene to pass it on to their child, but they do not typically show signs or symptoms of the disease.

Pseudopseudohypoparathyroidism can be best understood by comparing it to other conditions:

Hormone resistance is not present in pseudopseudohypoparathyroidism. Short stature may be present. Obesity is less common in pseudopseudohypoparathyroidism than in pseudohypoparathyroidism. Osteoma cutis may be present.

Type 4 RTA is not actually a tubular disorder at all nor does it have a clinical syndrome similar to the other types of RTA described above. It was included in the classification of renal tubular acidoses as it is associated with a mild (normal anion gap) metabolic acidosis due to a "physiological" reduction in proximal tubular ammonium excretion (impaired ammoniagenesis), which is secondary to hypoaldosteronism, and results in a decrease in urine buffering capacity. Its cardinal feature is hyperkalemia, and measured urinary acidification is normal, hence it is often called hyperkalemic RTA or tubular hyperkalemia.

Causes include:

- Aldosterone deficiency (hypoaldosteronism): Primary vs. hyporeninemic (including diabetic nephropathy)

- Aldosterone resistance

1. Drugs: NSAIDs, ACE inhibitors and ARBs, Eplerenone, Spironolactone, Trimethoprim, Pentamidine

2. Pseudohypoaldosteronism

The disorder is characterized by the following:

Individuals with Albright hereditary osteodystrophy exhibit short stature, characteristically shortened fourth and fifth metacarpals, rounded facies, and often mild intellectual deficiency. Albright hereditary osteodystrophy is commonly known as pseudohypoparathyroidism because the kidney responds as if parathyroid hormone were absent. Blood levels of parathyroid hormone are elevated in pseudohypoparathyroidism due to the hypocalcemia

Proximal RTA (pRTA) is caused by a failure of the proximal tubular cells to reabsorb filtered bicarbonate from the urine, leading to urinary bicarbonate wasting and subsequent acidemia. The distal intercalated cells function normally, so the acidemia is less severe than dRTA and the alpha intercalated cells can produce H to acidify the urine to a pH of less than 5.3. pRTA also has several causes, and may occasionally be present as a solitary defect, but is usually associated with a more generalized dysfunction of the proximal tubular cells called Fanconi syndrome, in which there is also phosphaturia, glycosuria, aminoaciduria, uricosuria, and tubular proteinuria.

The principle feature of Fanconi syndrome is bone demineralization (osteomalacia or rickets) due to phosphate wasting.

Primary hyperoxaluria is a rare condition (autosomal recessive), resulting in increased excretion of oxalate (up to 600mg a day from normal 50mg a day), with oxalate stones being common.

Symptoms (and signs) consistent with renal papillary necrosis are:

Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent, potentially lethal, monogenic human disorder. It is associated with large interfamilial and intrafamilial variability, which can be explained to a large extent by its genetic heterogeneity and modifier genes. It is also the most common of the inherited cystic kidney diseases — a group of disorders with related but distinct pathogenesis, characterized by the development of renal cysts and various extrarenal manifestations, which in case of ADPKD include cysts in other organs, such as the liver, seminal vesicles, pancreas, and arachnoid membrane, as well as other abnormalities, such as intracranial aneurysms and dolichoectasias, aortic root dilatation and aneurysms, mitral valve prolapse, and abdominal wall hernias. Over 50% of patients with ADPKD eventually develop end stage kidney disease and require dialysis or kidney transplantation. ADPKD is estimated to affect at least 1 in every 1000 individuals worldwide, making this disease the most common inherited kidney disorder with a diagnosed prevalence of 1:2000 and incidence of 1:3000-1:8000 in a global scale.

The causes of adult osteomalacia are varied, but ultimately result in a vitamin D deficiency:

Osteomalacia is a generalized bone condition in which there is inadequate mineralization of the bone. Many of the effects of the disease overlap with the more common osteoporosis, but the two diseases are significantly different. There are two main causes of osteomalacia:

1. insufficient calcium absorption from the intestine because of lack of dietary calcium or a deficiency of, or resistance to, the action of vitamin D

2. phosphate deficiency caused by increased renal losses.

Symptoms:

Osteomalacia in adults starts insidiously as aches and pains in the lumbar (lower back) region and thighs before spreading to the arms and ribs. The pain is symmetrical, non-radiating and accompanied by sensitivity in the involved bones. Proximal muscles are weak, and there is difficulty in climbing up stairs and getting up from a squatting position.

As a result of demineralization, the bones become less rigid. Physical signs include deformities like triradiate pelvis and lordosis. The patient has a typical "waddling" gait. However, these physical signs may derive from a previous osteomalacial state, since bones do not regain their original shape after they become deformed.

Pathologic fractures due to weight bearing may develop. Most of the time, the only alleged symptom is chronic fatigue, while bone aches are not spontaneous but only revealed by pressure or shocks.It differs from renal osteodystrophy, where the latter shows hyperphosphatemia.

Inborn errors of renal tubular transport are metabolic disorders which lead to impairment in the ability of solutes, such as salts or amino acids, to be transported across the brush border of the renal tubule. This results in disruptions of renal reabsorption.

Examples of these disorders include Iminoglycinuria, renal tubular acidosis and Gitelman syndrome.

Albright's hereditary osteodystrophy is a form of osteodystrophy, and is classified as the phenotype of pseudohypoparathyroidism type 1A; this is a condition in which the body does not respond to parathyroid hormone.

Acute tubular necrosis is classified as a "renal" (i.e. not pre-renal or post-renal) cause of acute kidney injury. Diagnosis is made by a FENa (fractional excretion of sodium) > 3% and presence of muddy casts (a type of granular cast) in urinalysis. On histopathology, there is usually "tubulorrhexis", that is, localized necrosis of the epithelial lining in renal tubules, with focal rupture or loss of basement membrane. Proximal tubule cells can shed with variable viability and not be purely "necrotic".