Pathogenesis of renal calculi

Urolithiasis involving the upper urinary tract is a multifactorial disease that remains a significant health problem. A variety of intrinsic and extrinsic factors influence the incidence of disease in individuals and in all populations. At the level of the kidney, natural physicochemical processes result in crystalluria and the formation and growth of stones. Urinary supersaturation of some degree must be present but its significance may be altered by changes in urinary volume, pH, epitaxial relationships, and the presence or absence of naturally occurring inhibitors. A variety of environmental parameters acting through effects on the local urinary conditions determine which patients among a group of people inherently at risk will form stones. The above factors are considered herein with regard to the four major types of stone disease encountered today.

Surgical classification of renal calculi

A classification of renal calculi is presented. 'C' describes the morphology, size and topography of the stone in five descriptive categories; the letters 'P', 'S', 'M', 'I' indicate the pelvis, the superior, middle and inferior calices, respectively, and complete the topographic description. The letter 'E' stands for the excretory tract; the symbols + and - are added to indicate the presence or absence of dilatation and the small letters e and i indicate the intra- and extrarenal position of the pelvis. 'R' points out the number of surgical recurrences. In conclusion, the letter 'P' indicates the functional status of the parenchyma, and the numbers 1, 2, 3 refer to a normally functioning kidney; moderate renal insufficiency, or serious renal insufficiency. 'U' symbolizes a solitary anatomical or functional kidney.

Ambulatory diagnostic evaluation of 389 recurrent renal stone formers. A proposal for clinical classification and investigation

389 consecutive renal stone formers (275 males, 114 females) were investigated in an out-patient stone clinic. Renal tubular acidosis (RTA) was found in 83 patients (22%). Proximal RTA was twice as common as the distal tubular type. The acidification defects were exclusively of the incomplete form with normal basal blood acidbase status. Main diagnoses besides RTA were primary hyperparathyroidism (3.5%), medullary sponge kidney (3.5%), infection induced stones (3%), urate stones (2%), intestinal disorder (1.5%) and cystinuria (0.5%). The metabolic evaluation was mainly based on 24 h urine sampling on a free diet. In 248 patients (64%) no distinct abnormality was considered to be primarily responsible for stone formation. Clinical and biochemical analysis of these so-called idiopathic stone formers disclosed a male preponderance (80%) and, compared to a non-stone-forming control group, a higher urinary calcium excretion, yet with a considerable overlap between the two groups. Hyperuricosuria and hyperoxaluria were rare findings. The conclusion of the study is given as a proposal for clinical classification and ambulatory investigation of renal stone formers.

Branched calculi: shapes and operative approaches

Branched calculi (infection stones) typically arise in intrarenal pelves. They expand to touch the pelvic wall and then grow peripherally, keeping contact with the walls of the pelvis and greater than or equal to 1 infundibula. Filling the infundibulum obstructs the calix and allows terminal expansion of the stone. From study of a series of stones such a sequence might be reconstructed. The shape of the calculus and collecting structures was traced and classified from excretory urograms of 50 consecutive renal units. The funnel pelvis, usually intrarenal, contained a stone either extending into the ureteropelvic junction (24 cases) or stopping short of it (9 cases). Pelvic or infundibular and caliceal dilatation around the stone was found in the remaining 8 and 9 cases, respectively. These patterns of growth of branched calculi directly bear on the approaches and technique for the operative removal. Because typical branched calculi arise in the intrarenal pelvis a high transverse intrahilar incision is necessary. Less intrahilar dissection is needed for cases in which the pelvis is dilated above and around the stone. Counter-incisions through the parenchyma or anatrophic nephrolithotomy is reserved for those patients with infundibular obstruction and resulting expanded caliceal stones.

[Calculi with large oxalate crystals (1st part)]

This is the introduction to the study of calculi which have large oxalate crystals. Calculi which are divided into three groups according to their other, non-oxalic compounds, which will be studied separately in three consecutive articles. Most of those large crystals are spectral and in spite of the fact that the calculi belonging to any group have the same components, the same formation mechanism and the same fundamental structures, they are not exact replicas of a prototype but, on the contrary, they all show a small difference from the previous and following ones which may lie in the duration of their development, in the amounts of their components or in the distribution of these components within them.

Nephrolithiasis: causes, classification, and management

The specific biochemical cause of calcium stone formation can now be reliably identified in close to 80% of cases. By permitting treatment to be targeted to the underlying condition, this has, in recent years, resulted in a documented reduction in stone recurrence. Less common types of nephrolithiasis--uric acid, cystine, and struvite stone formation--are also discussed and their management outlined.

Experimental study of marginal wedge resection and its practical application in the surgical therapy of staghorn calculi

A surgical procedure for staghorn calculi, which are inaccessible to conservative therapy, is described. It not only provides for complete elimination of the calculus but may also contribute to the prevention of recurrences. The technique of marginal wedge excision of the renal parenchyma, developed in animal studies, is described in detail and 11 surgical cases are reported. Removal of staghorn calculi was successful all throughout, and renal function remained unaffected by the intervention in all of the cases. Recurrences were confined to a single case. The procedure is safe, it involves no greater surgical strain than does marginal nephrotomy, but its short-term metaphylactic results seem more promising. Assessment of the long-term results awaits further observations.

Renal lithiasis in Lebanon: I--the chemical types of urinary calculi

The results of chemical analyses of 429 urinary calculi are presented and classified according to chemical composition. Some of the general features of the different chemical types of the stones are discussed. Although the general distribution of the chemical types of stones in Lebanon is essentially similar to that reported from other countries, the two striking features of this series are: (1) a relatively lower incidence of infection stones (i.e. stones containing magnesium ammonium phosphate) and (2) a relatively higher incidence of stones containing a mixture of uric acid and calcium oxalate and/or calcium phosphate.

Renal lithiasis: a practical approach

Management of most patients with calculous disease has been less than ideal in the past. Too often therapeutic efforts were limited to symptomatic calculi. Stones were allowed to pass or were removed, metabolic studies were incomplete, victims were dismissed and forgotten, and prophylactic measures were negligible and usually confined to milk restriction and use of distilled water. More patients were crippled with and died of recurrent calculous disease, urinary infection and progressive renal insufficiency than from any other upper urinary tract abnormality. During the last decade the development of a renal stone clinic at this institution has allowed a nephrourologic approach to the management of urolithiasis. This account of classification, diagnosis and management of the various syndromes associated with urolithiasis is based on the experiences gained during the last decade with this common but ill-understood urologic problem.

[Automatic data processing in our dispensary care for patients with nephrolithiasis]

It is reported on an advantageous mechanical data processing in nephrolithiases, which was organised by the authors and is performed in form of a "nephrolith-dispensary-card" with filtration of the data and mechanical questioning.

Staghorn calculi of the kidneys. A. Clinical review

A series of 91 staghorn calculi are reviewed. Possible aetiological factors are analysed. A high incidence of hypercalciuria was found, and the significance of this is discussed. The rates of complete stone clearance after conservative surgery are considered for different types of staghorn calculus and it is felt that local circulatory arrest with kidney cooling may be of value in removing stones due to Proteus. The place of elective nephrectomy in the management of staghorn calculi is discussed. Nephrectomy may be the treatment of choice in the management of large, unilateral stones in older patients.

Matrix and the infective renal calculus

From the basis of an examination of the literature, and on a personal exerience of the surgical treatment of 100 cases of calculus disease, the suggestion is made that 2 distinct mechanisms of calculogenesis should be recognised. Calculi of metabolic origin should be considered as having an entirely distinct aetiological mechanism. Phosphatic calculi are apparently determined by the existence of urinary tract infection. Partial nephrectomy does not seem indicated for either type of disease.